Electrolyte for synergistically stabilizing positive electrode iodine multi-electron reaction by using four combined zinc salts and high-surface-capacity zinc-iodine soft package battery

Abstract

The invention relates to an electrolyte for synergistically stabilizing positive electrode iodine multi-electron reaction through four-combination zinc salt and a high-surface-capacity zinc-iodine soft package battery. The electrolyte comprises the four-combination zinc salt and water, in the electrolyte, the total concentration of zinc ions in the four combinations of zinc salts is 2 + / -0.2 mol / L; the four-combination zinc salt is a four-combination zinc salt; the SO4 < 2-> in the electrolyte buffers the pH value of a system, so that side reaction of a negative electrode is reduced; cH3COO <-> can be cross-linked with I3 <->, so that shuttling of polyiodide is inhibited, and reversibility of a two-electron reaction is enhanced; bromide ions Br <-> in the electrolyte are chemically combined with I < + > through isohalogen to excite four-electron reaction; the trifluoromethanesulfonate OTf <-> with strong electronegativity surrounds the positive electricity I < + > by virtue of an ion atmosphere effect, so that active water molecule attack hydrolysis failure is avoided, a synergistic stable positive electrode iodine multi-electron reaction is realized, and the high-surface-capacity zinc-iodine soft package battery is beneficial to promoting the development of the zinc-iodine battery to practical application.

Description

Technical Field

[0001] This invention relates to the field of zinc-iodine pouch batteries, and in particular to an electrolyte that uses four zinc salts to synergistically stabilize the positive electrode iodine multi-electron reaction and a high-area-capacity zinc-iodine pouch battery. Background Technology

[0002] Zinc-iodine batteries, as a next-generation energy storage technology, have become a research hotspot in the field of large-scale energy storage due to their low cost and environmental friendliness. Furthermore, iodine cathodes also possess multi-valence state characteristics, such as I₂. - I 0 I + These factors, such as the conventional two-electron reaction of iodine, are beneficial for improving the energy density of zinc-iodine batteries. This provides a suitable redox potential and theoretical capacity (0.54 V, 211 mAh g⁻¹). -1 If the tetraelectron reaction of iodine is further stimulated... The redox potential and theoretical capacity can be increased to 1.07 V and 422 mAh g, respectively. -1 It surpasses the cathode materials of most aqueous zinc-based batteries.

[0003] Nevertheless, the practical application of multi-electron transfer zinc-iodine batteries still faces significant challenges. In the two-electron reaction process, the reaction product I₂ readily reacts with I₂. - Combined to form soluble polyiodide I3 - I3 - It easily diffuses to the negative electrode for deactivation, reducing the reversibility of the two-electron reaction. In the four-electron reaction pathway, intermediate I... + It is highly susceptible to attack by active water molecules, hydrolyzing to generate I2, which also reduces coulombic efficiency and cycle performance. Currently, single electrolyte additives are often used, which lack the ability to synergistically regulate the multi-valence reactions of iodine, making it difficult to simultaneously optimize the thermodynamic and kinetic processes of two-electron and four-electron reactions. In addition, the introduction of additional components also increases battery impedance, making it only suitable for laboratory button cell research and unable to meet the high areal capacity requirements of practical zinc-iodine pouch batteries.

[0004] To obtain high-capacity multi-electron transfer zinc-iodine pouch cells, while simultaneously addressing the polyiodide shuttle effect, I... + Addressing hydrolysis failure and reducing the use of additional components are crucial. Zinc salts, as an important component of the electrolyte, not only provide sufficient zinc ions but also regulate electrode interface reactions without increasing impedance. Therefore, optimizing the zinc salt composition of the electrolyte is an important approach to achieving high areal capacity, multi-electron transfer zinc-iodine pouch cells. Summary of the Invention

[0005] To address the polyiodide shuttle effect and Ig in the multi-electron transfer process of existing zinc-iodine pouch batteries+ To address the problem of hydrolysis failure, this invention provides an electrolyte that uses a four-combination zinc salt to synergistically stabilize the positive electrode iodine multi-electron reaction.

[0006] This invention is achieved through the following technical solution:

[0007] An electrolyte containing four zinc salts in synergistic stabilization of the positive electrode iodine multi-electron reaction, the electrolyte comprising four zinc salts and water;

[0008] In the electrolyte, the total zinc ion concentration of the four zinc salt combinations is 2 ± 0.2 mol / L.

[0009] Preferably, the four zinc salts are zinc sulfate, zinc acetate, zinc bromide, and zinc trifluoromethanesulfonate, and the molar ratio of zinc sulfate, zinc acetate, zinc bromide, and zinc trifluoromethanesulfonate is (0.8-1.0):(0.2-0.4):(0.4-0.6):(0.2-0.4).

[0010] Preferably, the preparation method includes:

[0011] Four zinc salts were dissolved in water and then magnetically stirred to obtain an electrolyte in which the four zinc salts synergistically stabilized the positive electrode iodine multi-electron reaction.

[0012] The above-mentioned application of an electrolyte that uses four zinc salts to synergistically stabilize the positive electrode iodine multi-electron reaction in the preparation of a four-electron zinc-iodine soft-pack battery.

[0013] A zinc-iodine soft-pack battery, wherein the zinc-iodine soft-pack battery contains an electrolyte containing the aforementioned four-combination zinc salts that synergistically stabilize the positive electrode iodine multi-electron reaction.

[0014] A zinc-iodine soft-pack battery, wherein the zinc-iodine soft-pack battery uses an iodine@carbon composite material as the positive electrode, metallic zinc as the negative electrode, a glass fiber membrane as the separator, and an electrolyte containing a four-combination zinc salt synergistically stabilizing the positive electrode iodine multi-electron reaction as the electrolyte.

[0015] Preferably, the carbon in the iodine@carbon composite material is activated carbon with adsorption properties.

[0016] According to the above-mentioned method for preparing a zinc-iodine soft-pack battery, the assembly is carried out in the following order:

[0017] (1) Preparation of the positive electrode sheet:

[0018] S1. Grind and mix iodine and carbon, then heat at 150-200℃ for adsorption;

[0019] S2. After adsorption is complete, heat at 60-100℃ in an open environment to obtain iodine@carbon composite material;

[0020] S3. Mix the above-mentioned iodine@carbon composite material, conductive agent and binder in a uniform ratio, and add deionized water to disperse and form a slurry;

[0021] S4. Apply the above slurry onto graphite felt and dry it to obtain the positive electrode sheet.

[0022] (2) Cut the above positive electrode sheet, negative electrode zinc foil and separator;

[0023] (3) The separator and the prepared positive electrode sheet are wetted with electrolyte, and then the positive electrode sheet and the negative zinc foil are separated by the separator. The battery is placed in an aluminum-plastic film bag and sealed to obtain a four-electron zinc-iodine soft pack battery.

[0024] Preferably, the areal loading of iodine in the positive electrode is 30 mg / cm³. -2 ;

[0025] And / or, the conductive agent is Ketjen Black; the binder is sodium carboxymethyl cellulose; and the diaphragm is a glass fiber diaphragm.

[0026] Preferably, the mass ratio of iodine to carbon in S1 is 1:(0.5-2).

[0027] And / or, the adsorption conditions in S1 are adsorption by heating at 180°C for 12 hours;

[0028] And / or, the heating conditions in S2 are heating at 80°C in an open environment for 6 hours;

[0029] And / or, the iodine@carbon composite material, conductive agent, and binder in S3 are uniformly mixed in a mass ratio of 8:1:1;

[0030] And / or, the thickness of the graphite felt in S4 is 5 mm;

[0031] And / or, in step (2), the positive electrode sheet is cut to a size of 4*5cm, the negative electrode zinc foil is cut to a size of 4.5*5.5cm, and the separator is cut to a size of 5*6cm.

[0032] The beneficial effects of this invention are:

[0033] This invention provides an electrolyte in which four zinc salts synergistically stabilize the positive electrode iodine multi-electron reaction, wherein SO4 in the electrolyte... 2- Buffering the pH of the system reduces negative electrode side reactions; CH3COO - Capable of crosslinking I3 - It inhibits polyiodide shuttle and enhances the reversibility of two-electron reactions; the bromide ions (Br) in the electrolyte - Through isohalogen chemical binding of I + It triggers a four-electron reaction; the strongly negatively charged trifluoromethanesulfonate ion OTf -By utilizing the "ion atmosphere effect", surround positively charged I + This avoids the attack and hydrolysis failure by active water molecules, and achieves a synergistic and stable positive electrode iodine multi-electron reaction.

[0034] This invention provides a high-area-capacity zinc-iodine soft-pack battery (~14 mAh cm⁻¹). -2 It can stably cycle 100 times, which is conducive to promoting the practical application of zinc-iodine batteries.

[0035] In addition, the main raw materials used in this invention are widely available, inexpensive and environmentally friendly. The entire electrolyte preparation process is carried out at room temperature and pressure, and is simple to operate, safe and pollution-free.

[0036] This invention starts with zinc salt, a component of the electrolyte itself, and provides a simple and efficient electrolyte design strategy without the need to introduce other components. Attached Figure Description

[0037] Figure 1 This is a pH distribution diagram of the electrolytes obtained in Examples 1-3 of the present invention;

[0038] Figure 2 This is a corrosion current density diagram of the zinc-zinc symmetric cell in Example 1 of the present invention;

[0039] Figure 3 This is a corrosion current density diagram of the zinc-zinc symmetric cell in Example 2 of the present invention;

[0040] Figure 4 This is a corrosion current density diagram of the zinc-zinc symmetric cell in Example 3 of the present invention;

[0041] Figure 5 This is the UV-Vis absorption spectrum of the electrolyte obtained in Example 4 of this invention after soaking I2@AC cathode for 24 hours;

[0042] Figure 6 The image shows the UV-Vis absorption spectrum of the electrolyte obtained in Example 5 of this invention after soaking the I2@AC cathode for 24 hours.

[0043] Figure 7 This is the UV-Vis absorption spectrum of the electrolyte obtained in Example 6 of this invention after soaking I2@AC cathode for 24 hours;

[0044] Figure 8 This is a charge-discharge curve of a zinc-iodine soft-pack battery with the electrolyte obtained in Example 7 of the present invention;

[0045] Figure 9 This is a charge-discharge curve of a zinc-iodine soft-pack battery with the electrolyte obtained in Example 8 of the present invention;

[0046] Figure 10This is a charge-discharge curve of a zinc-iodine soft-pack battery with the electrolyte obtained in Example 9 of the present invention;

[0047] Figure 11 The coulombic efficiency diagrams of the zinc-iodine soft-pack batteries with electrolytes obtained in Examples 10-12 of this invention are shown.

[0048] Figure 12 The circuit performance diagram of the zinc-iodine soft-pack battery with the electrolyte obtained in Example 10 of the present invention is shown.

[0049] Figure 13 This is a cycle performance diagram of the zinc-iodine soft-pack battery with the electrolyte obtained in Example 11 of the present invention;

[0050] Figure 14 This is a cycle performance diagram of the zinc-iodine soft-pack battery with the electrolyte obtained in Example 12 of the present invention; Detailed Implementation

[0051] The present invention will be described in detail below with reference to specific embodiments and examples, thereby making the advantages and various effects of the present invention more clearly apparent. Those skilled in the art should understand that these specific embodiments and examples are for illustrative purposes only and are not intended to limit the present invention.

[0052] Throughout this specification, unless otherwise specified, the terminology used herein should be understood as having the meaning commonly used in the art. Therefore, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. In the event of any conflict, this specification shall prevail.

[0053] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0054] The technical principle of this invention is as follows:

[0055] An electrolyte containing four zinc salts in synergistic stabilization of the positive electrode iodine multi-electron reaction, the electrolyte comprising four zinc salts and water;

[0056] In the electrolyte, the total zinc ion concentration of the four zinc salt combinations is 2 ± 0.2 mol / L.

[0057] Preferably, the four zinc salts are zinc sulfate, zinc acetate, zinc bromide, and zinc trifluoromethanesulfonate, and the molar ratio of zinc sulfate, zinc acetate, zinc bromide, and zinc trifluoromethanesulfonate is (0.8-1.0):(0.2-0.4):(0.4-0.6):(0.2-0.4).

[0058] In this invention, the advantage of having a total zinc ion concentration of 2 ± 0.2 mol / L in the four zinc salt combinations is that it can reduce the zinc ion concentration gradient at the negative electrode interface. When the concentration is too low, zinc dendrites are easily generated, which can puncture the separator and cause a short circuit in the battery. When the concentration is too high, it can lead to excessive viscosity and performance degradation.

[0059] In this invention, the four-component zinc salt is composed of four of the following: zinc sulfate, zinc acetate, zinc bromide, and zinc trifluoromethanesulfonate. (SO4) 2- Buffering the pH of the system reduces negative electrode side reactions; CH3COO - Capable of crosslinking I3 - It inhibits polyiodide shuttle and enhances the reversibility of two-electron reactions; the bromide ions (Br) in the electrolyte - Through isohalogen chemical binding of I + It triggers a four-electron reaction; the strongly negatively charged trifluoromethanesulfonate ion OTf - By utilizing the "ion atmosphere effect", surround positively charged I + This prevents active water molecules from attacking and degrading the hydrolysis process.

[0060] Based on the same inventive concept, the present invention provides a high-area-capacity zinc-iodine soft-pack battery, wherein the zinc-iodine soft-pack battery uses iodine@activated carbon composite material as the positive electrode, metallic zinc as the negative electrode, glass fiber membrane as the separator, and the above-mentioned electrolyte of a four-combination zinc salt synergistically stabilizing the positive electrode iodine multi-electron reaction as the electrolyte.

[0061] Furthermore, the high-area-capacity zinc-iodine soft-pack battery is prepared by the following method:

[0062] Preparation of the positive electrode sheet:

[0063] Iodine and activated carbon were manually ground and mixed at a mass ratio of 1:1, and then heated at 180℃ for 12 hours for adsorption.

[0064] After adsorption was complete, the mixture was heated at 80°C for 6 hours in an open environment to obtain an iodine@activated carbon composite material.

[0065] The above-mentioned iodine@activated carbon composite material, conductive agent and binder are uniformly mixed at a mass ratio of 8:1:1, and deionized water is added to disperse and form a slurry.

[0066] The above slurry is applied to a 5mm thick graphite felt and dried to obtain the positive electrode sheet.

[0067] The positive electrode sheet is cut to a size of 4*5cm, the negative electrode zinc foil to a size of 4.5*5.5cm, and the separator to a size of 5*6cm.

[0068] The electrolyte used to stabilize the positive electrode iodine multi-electron reaction of the four zinc salt combinations described above is used to wet the separator and the prepared positive electrode sheet. Then, the positive electrode sheet is separated from the negative zinc foil by the separator, and the battery is placed in an aluminum-plastic film bag to encapsulate it, thus obtaining an aqueous zinc-iodine soft-pack battery.

[0069] Preferably, the areal loading of iodine in the positive electrode is approximately 30 mg / cm³. -2 .

[0070] Preferably, the conductive agent is Ketjen Black; the binder is sodium carboxymethyl cellulose; and the diaphragm is a glass fiber diaphragm.

[0071] In this invention, the preferred mass ratio of iodine to activated carbon is 1:1, which ensures that the iodine nanoparticles are completely adsorbed in the pore structure of the activated carbon. If the mass ratio is too high, the iodine particles will agglomerate, while if the mass ratio is too low, the content of active substances in the iodine@activated carbon composite material will be too low.

[0072] In this invention, the advantage of heating at 80°C for 6 hours in an open environment is that it can sublimate the iodine that is not adsorbed on the activated carbon, thereby improving the iodine utilization rate.

[0073] In this invention, the preferred mass ratio of iodine@activated carbon composite material, conductive agent, and binder is 8:1:1, which has the advantage of obtaining a stable positive electrode sheet and good full-cell cycle performance.

[0074] The following will provide a detailed description of the electrolyte for synergistic stabilization of the positive electrode iodine multi-electron reaction by four zinc salt combinations and the high-capacity zinc-iodine soft-pack battery of the present invention, in conjunction with embodiments and experimental data.

[0075] In this series of experimental studies, the Xinwei Battery Testing System was used to conduct a detailed evaluation of battery performance. To explore the impact of different electrolytes on battery performance, four common low-cost zinc salts—zinc sulfate, zinc acetate, zinc bromide, and zinc trifluoromethanesulfonate—were innovatively combined to form a four-combination zinc salt electrolyte system. This four-combination zinc salt electrolyte system aims to synergistically stabilize the multi-electron reaction of the positive electrode iodine, thereby optimizing the performance of zinc-iodine pouch batteries.

[0076] In the examples and comparative examples, zinc-iodine pouch cells were assembled at room temperature, and the current density was set to 0.5C (1C = 422 mA g). -1 The voltage test range is 0.7 V to 1.85 V to evaluate its coulombic efficiency and cycle performance.

[0077] Unless otherwise specified, the methods used in this invention are all conventional.

[0078] Example 1

[0079] Step 1: Weigh 4.601g zinc sulfate, 1.317g zinc acetate, 2.252g zinc bromide, and 2.181g zinc trifluoromethanesulfonate, add them together to 15mL of water, stir until clear, transfer the solution to a volumetric flask, and make up to 20mL to obtain a four-component zinc salt electrolyte consisting of 0.8M zinc sulfate + 0.3M zinc acetate + 0.5M zinc bromide + 0.3M zinc trifluoromethanesulfonate.

[0080] Step 2: Iodine and activated carbon are manually ground and mixed at a mass ratio of 1:1, then heated at 180℃ for 12 hours for adsorption, and finally heated at 80℃ in an open environment for 6 hours to obtain the iodine@activated carbon composite material. The iodine@activated carbon composite material, conductive agent, and binder are uniformly mixed at a mass ratio of 8:1:1, and deionized water is added to disperse them into a slurry. This slurry is then coated onto a 5mm thick graphite felt and dried to obtain the positive electrode sheet.

[0081] Step 3: Assemble zinc-iodine pouch cells using the prepared positive electrode, zinc foil, and electrolyte.

[0082] Example 2

[0083] Step 1: Weigh 5.176g zinc sulfate, 1.317g zinc acetate, 2.252g zinc bromide, and 2.181g zinc trifluoromethanesulfonate, add them together to 15mL of water, stir until clear, transfer the solution to a volumetric flask, and make up to 20mL to obtain a four-component zinc salt electrolyte consisting of 0.9M zinc sulfate + 0.3M zinc acetate + 0.5M zinc bromide + 0.3M zinc trifluoromethanesulfonate.

[0084] Step 2: Iodine and activated carbon are manually ground and mixed at a mass ratio of 1:1, then heated at 180℃ for 12 hours for adsorption, and finally heated at 80℃ in an open environment for 6 hours to obtain the iodine@activated carbon composite material. The iodine@activated carbon composite material, conductive agent, and binder are uniformly mixed at a mass ratio of 8:1:1, and deionized water is added to disperse them into a slurry. This slurry is then coated onto a 5mm thick graphite felt and dried to obtain the positive electrode sheet (the amount of each raw material used in the positive electrode material is the same as in Example 1).

[0085] Step 3: Assemble zinc-iodine pouch cells using the prepared positive electrode, zinc foil, and electrolyte.

[0086] Example 3

[0087] Step 1: Weigh 5.751g zinc sulfate, 1.317g zinc acetate, 2.252g zinc bromide, and 2.181g zinc trifluoromethanesulfonate, add them together to 15mL of water, stir until clear, transfer the solution to a volumetric flask, and make up to 20mL to obtain a four-component zinc salt electrolyte consisting of 1.0M zinc sulfate + 0.3M zinc acetate + 0.5M zinc bromide + 0.3M zinc trifluoromethanesulfonate.

[0088] Step 2: Iodine and activated carbon are manually ground and mixed at a mass ratio of 1:1, then heated at 180℃ for 12 hours for adsorption, and finally heated at 80℃ in an open environment for 6 hours to obtain the iodine@activated carbon composite material. The iodine@activated carbon composite material, conductive agent, and binder are uniformly mixed at a mass ratio of 8:1:1, and deionized water is added to disperse them into a slurry. This slurry is then coated onto a 5mm thick graphite felt and dried to obtain the positive electrode sheet (the amount of each raw material used in the positive electrode material is the same as in Example 1).

[0089] Step 3: Assemble zinc-iodine pouch cells using the prepared positive electrode, zinc foil, and electrolyte.

[0090] Example 4

[0091] Step 1: Weigh 5.176g zinc sulfate, 0.878g zinc acetate, 2.252g zinc bromide, and 2.181g zinc trifluoromethanesulfonate, add them together to 15mL of water, stir until clear, transfer the solution to a volumetric flask, and make up to 20mL to obtain a four-component zinc salt electrolyte consisting of 0.9M zinc sulfate + 0.2M zinc acetate + 0.5M zinc bromide + 0.3M zinc trifluoromethanesulfonate.

[0092] Step 2: Iodine and activated carbon are manually ground and mixed at a mass ratio of 1:1, then heated at 180℃ for 12 hours for adsorption, and finally heated at 80℃ in an open environment for 6 hours to obtain the iodine@activated carbon composite material. The iodine@activated carbon composite material, conductive agent, and binder are uniformly mixed at a mass ratio of 8:1:1, and deionized water is added to disperse them into a slurry. This slurry is then coated onto a 5mm thick graphite felt and dried to obtain the positive electrode sheet (the amount of each raw material used in the positive electrode material is the same as in Example 1).

[0093] Step 3: Assemble zinc-iodine pouch cells using the prepared positive electrode, zinc foil, and electrolyte.

[0094] Example 5

[0095] Step 1: Weigh 5.751g zinc sulfate, 1.317g zinc acetate, 2.252g zinc bromide, and 2.181g zinc trifluoromethanesulfonate, add them together to 15mL of water, stir until clear, transfer the solution to a volumetric flask, and make up to 20mL to obtain a four-component zinc salt electrolyte consisting of 1.0M zinc sulfate + 0.3M zinc acetate + 0.5M zinc bromide + 0.3M zinc trifluoromethanesulfonate.

[0096] Step 2: Iodine and activated carbon are manually ground and mixed at a mass ratio of 1:1, then heated at 180℃ for 12 hours for adsorption, and finally heated at 80℃ in an open environment for 6 hours to obtain the iodine@activated carbon composite material. The iodine@activated carbon composite material, conductive agent, and binder are uniformly mixed at a mass ratio of 8:1:1, and deionized water is added to disperse them into a slurry. This slurry is then coated onto a 5mm thick graphite felt and dried to obtain the positive electrode sheet (the amount of each raw material used in the positive electrode material is the same as in Example 1).

[0097] Step 3: Assemble zinc-iodine pouch cells using the prepared positive electrode, zinc foil, and electrolyte.

[0098] Example 6

[0099] Step 1: Weigh 5.176g zinc sulfate, 1.756g zinc acetate, 2.252g zinc bromide, and 2.181g zinc trifluoromethanesulfonate, add them together to 15mL of water, stir until clear, transfer the solution to a volumetric flask, and make up to 20mL to obtain a four-component zinc salt electrolyte consisting of 0.9M zinc sulfate + 0.4M zinc acetate + 0.5M zinc bromide + 0.3M zinc trifluoromethanesulfonate.

[0100] Step 2: Iodine and activated carbon are manually ground and mixed at a mass ratio of 1:1, then heated at 180℃ for 12 hours for adsorption, and finally heated at 80℃ in an open environment for 6 hours to obtain the iodine@activated carbon composite material. The iodine@activated carbon composite material, conductive agent, and binder are uniformly mixed at a mass ratio of 8:1:1, and deionized water is added to disperse them into a slurry. This slurry is then coated onto a 5mm thick graphite felt and dried to obtain the positive electrode sheet (the amount of each raw material used in the positive electrode material is the same as in Example 1).

[0101] Step 3: Assemble zinc-iodine pouch cells using the prepared positive electrode, zinc foil, and electrolyte.

[0102] Example 7

[0103] Step 1: Weigh 5.176g zinc sulfate, 1.317g zinc acetate, 1.802g zinc bromide, and 2.181g zinc trifluoromethanesulfonate, add them together to 15mL of water, stir until clear, transfer the solution to a volumetric flask, and make up to 20mL to obtain a four-component zinc salt electrolyte consisting of 0.9M zinc sulfate + 0.3M zinc acetate + 0.4M zinc bromide + 0.3M zinc trifluoromethanesulfonate.

[0104] Step 2: Iodine and activated carbon are manually ground and mixed at a mass ratio of 1:1, then heated at 180℃ for 12 hours for adsorption, and finally heated at 80℃ in an open environment for 6 hours to obtain the iodine@activated carbon composite material. The iodine@activated carbon composite material, conductive agent, and binder are uniformly mixed at a mass ratio of 8:1:1, and deionized water is added to disperse them into a slurry. This slurry is then coated onto a 5mm thick graphite felt and dried to obtain the positive electrode sheet (the amount of each raw material used in the positive electrode material is the same as in Example 1).

[0105] Step 3: Assemble zinc-iodine pouch cells using the prepared positive electrode, zinc foil, and electrolyte.

[0106] Example 8

[0107] Step 1: Weigh 5.751g zinc sulfate, 1.756g zinc acetate, 2.252g zinc bromide, and 2.181g zinc trifluoromethanesulfonate, add them together to 15mL of water, stir until clear, transfer the solution to a volumetric flask, and make up to 20mL to obtain a four-component zinc salt electrolyte consisting of 1.0M zinc sulfate + 0.4M zinc acetate + 0.5M zinc bromide + 0.3M zinc trifluoromethanesulfonate.

[0108] Step 2: Iodine and activated carbon are manually ground and mixed at a mass ratio of 1:1, then heated at 180℃ for 12 hours for adsorption, and finally heated at 80℃ in an open environment for 6 hours to obtain the iodine@activated carbon composite material. The iodine@activated carbon composite material, conductive agent, and binder are uniformly mixed at a mass ratio of 8:1:1, and deionized water is added to disperse them into a slurry. This slurry is then coated onto a 5mm thick graphite felt and dried to obtain the positive electrode sheet (the amount of each raw material used in the positive electrode material is the same as in Example 1).

[0109] Step 3: Assemble zinc-iodine pouch cells using the prepared positive electrode, zinc foil, and electrolyte.

[0110] Example 9

[0111] Step 1: Weigh 5.176g zinc sulfate, 1.317g zinc acetate, 2.702g zinc bromide, and 2.181g zinc trifluoromethanesulfonate, add them together to 15mL of water, stir until clear, transfer the solution to a volumetric flask, and make up to 20mL to obtain a four-component zinc salt electrolyte consisting of 0.9M zinc sulfate + 0.3M zinc acetate + 0.6M zinc bromide + 0.3M zinc trifluoromethanesulfonate.

[0112] Step 2: Iodine and activated carbon are manually ground and mixed at a mass ratio of 1:1, then heated at 180℃ for 12 hours for adsorption, and finally heated at 80℃ in an open environment for 6 hours to obtain the iodine@activated carbon composite material. The iodine@activated carbon composite material, conductive agent, and binder are uniformly mixed at a mass ratio of 8:1:1, and deionized water is added to disperse them into a slurry. This slurry is then coated onto a 5mm thick graphite felt and dried to obtain the positive electrode sheet (the amount of each raw material used in the positive electrode material is the same as in Example 1).

[0113] Step 3: Assemble zinc-iodine pouch cells using the prepared positive electrode, zinc foil, and electrolyte.

[0114] Example 10

[0115] Step 1: Weigh 5.176g zinc sulfate, 1.317g zinc acetate, 2.252g zinc bromide, and 1.454g zinc trifluoromethanesulfonate, add them together to 15mL of water, stir until clear, transfer the solution to a volumetric flask, and make up to 20mL to obtain a four-component zinc salt electrolyte consisting of 0.9M zinc sulfate + 0.3M zinc acetate + 0.5M zinc bromide + 0.2M zinc trifluoromethanesulfonate.

[0116] Step 2: Iodine and activated carbon are manually ground and mixed at a mass ratio of 1:1, then heated at 180℃ for 12 hours for adsorption, and finally heated at 80℃ in an open environment for 6 hours to obtain the iodine@activated carbon composite material. The iodine@activated carbon composite material, conductive agent, and binder are uniformly mixed at a mass ratio of 8:1:1, and deionized water is added to disperse them into a slurry. This slurry is then coated onto a 5mm thick graphite felt and dried to obtain the positive electrode sheet (the amount of each raw material used in the positive electrode material is the same as in Example 1).

[0117] Step 3: Assemble zinc-iodine pouch cells using the prepared positive electrode, zinc foil, and electrolyte.

[0118] Example 11

[0119] Step 1: Weigh 5.751g zinc sulfate, 1.756g zinc acetate, 2.702g zinc bromide, and 2.181g zinc trifluoromethanesulfonate, add them together to 15mL of water, stir until clear, transfer the solution to a volumetric flask, and make up to 20mL to obtain a four-component zinc salt electrolyte consisting of 1.0M zinc sulfate + 0.4M zinc acetate + 0.6M zinc bromide + 0.3M zinc trifluoromethanesulfonate.

[0120] Step 2: Iodine and activated carbon are manually ground and mixed at a mass ratio of 1:1, then heated at 180℃ for 12 hours for adsorption, and finally heated at 80℃ in an open environment for 6 hours to obtain the iodine@activated carbon composite material. The iodine@activated carbon composite material, conductive agent, and binder are uniformly mixed at a mass ratio of 8:1:1, and deionized water is added to disperse them into a slurry. This slurry is then coated onto a 5mm thick graphite felt and dried to obtain the positive electrode sheet (the amount of each raw material used in the positive electrode material is the same as in Example 1).

[0121] Step 3: Assemble zinc-iodine pouch cells using the prepared positive electrode, zinc foil, and electrolyte.

[0122] Example 12

[0123] Step 1: Weigh 5.176g zinc sulfate, 1.317g zinc acetate, 2.252g zinc bromide, and 2.908g zinc trifluoromethanesulfonate, add them together to 15mL of water, stir until clear, transfer the solution to a volumetric flask, and make up to 20mL to obtain a four-component zinc salt electrolyte consisting of 0.9M zinc sulfate + 0.3M zinc acetate + 0.5M zinc bromide + 0.4M zinc trifluoromethanesulfonate.

[0124] Step 2: Iodine and activated carbon are manually ground and mixed at a mass ratio of 1:1, then heated at 180℃ for 12 hours for adsorption, and finally heated at 80℃ in an open environment for 6 hours to obtain the iodine@activated carbon composite material. The iodine@activated carbon composite material, conductive agent, and binder are uniformly mixed at a mass ratio of 8:1:1, and deionized water is added to disperse them into a slurry. This slurry is then coated onto a 5mm thick graphite felt and dried to obtain the positive electrode sheet (the amount of each raw material used in the positive electrode material is the same as in Example 1).

[0125] Step 3: Assemble zinc-iodine pouch cells using the prepared positive electrode, zinc foil, and electrolyte.

[0126] Table 1 is a statistical table of the performance of zinc-iodine pouch batteries using the four-combination zinc salt electrolytes of all embodiments of the present invention. As can be seen from the table, all embodiments exhibit excellent performance in terms of specific capacity, coulombic efficiency, areal capacity, and cycle stability, indicating that the four-combination zinc salts can synergistically stabilize the two-electron and four-electron reactions of iodine in the cathode, i.e., suppress the polyiodide shuttle effect and I... + Hydrolysis issues. However, there are also differences between the various embodiments, as detailed below:

[0127] Table 1. Performance of zinc-iodine pouch cells using the combined zinc salt electrolyte in Example 4 of this invention.

[0128]

[0129] Figures 1-4The figures show the pH values ​​of the electrolytes obtained in Examples 1-3 and the corresponding corrosion current densities of the zinc-zinc symmetric cells. As can be seen from the figures, with increasing zinc sulfate concentration, the pH values ​​of the four zinc salt electrolyte combinations gradually tend towards neutral, and the negative electrode corrosion current densities of the zinc-zinc symmetric cells assembled with the corresponding electrolytes decrease sequentially, indicating that SO42-... 2- It can buffer the pH of the system and reduce negative electrode side reactions.

[0130] Figures 5-7 The figures show the UV-Vis absorption spectra of the electrolytes obtained in Examples 4-6 after soaking the I2@AC cathode for 24 hours. As can be seen from the figures, with increasing zinc acetate concentration, the four zinc salt electrolyte combinations produce polyiodide I3 after soaking the I2@AC cathode for 24 hours. - The concentration decreases sequentially, indicating that CH3COO - Capable of crosslinking I3 - This inhibits the shuttle of polyiodide to the negative electrode, thereby enhancing the reversibility of the iodine two-electron reaction at the positive electrode.

[0131] Figures 8-10 The figures show the charge-discharge curves of the zinc-iodine pouch cells with the electrolytes obtained in Examples 7-9. As can be seen from the figures, the zinc-iodine pouch cells exhibit two distinct pairs of redox reactions, corresponding to 2I... - → I2, I2 → 2I + The reaction. When the zinc bromide concentration is below 0.5 M, the specific capacity of the zinc-iodine battery is lower than the theoretical capacity of the iodine tetraelectron reaction, which is 422 mAh g. -1 When the zinc bromide concentration exceeds 0.5 M, the specific capacity of the zinc-iodine battery exceeds the theoretical capacity, indicating that the bromide ion concentration (Br) increases significantly. - Through isohalogen chemical binding of I + This triggers a four-electron reaction of iodine at the positive electrode.

[0132] Figures 11-14 The figures show the coulombic efficiency and cycle performance data of the zinc-iodine pouch cells with the electrolytes obtained in Examples 10-12. As can be seen from the figures, the coulombic efficiency exhibits a parabolic curve with increasing zinc trifluoromethanesulfonate concentration, indicating that within a certain concentration range, the strongly negatively charged zinc trifluoromethanesulfonate ion (OTf) increases significantly. - It can prevent active water molecules from attacking I + Hydrolysis fails. However, above a certain concentration, OTf molecules with larger molecular sizes... - Ions will suppress I + The redox reaction of ions is reversible. Furthermore, data from the cycle performance of zinc-iodine pouch cells indicate that a moderate amount of trifluoromethanesulfonate can achieve an initial areal capacity of approximately 14 mAh cm⁻¹. -2Furthermore, after 100 cycles, the coulombic efficiency remained around 98%, demonstrating excellent cycle stability. Therefore, the strongly negatively charged trifluoromethanesulfonate OTf- can surround the positively charged I- through the "ionic atmosphere effect." + It avoids hydrolysis failure caused by active water molecules, and has high coulombic efficiency and cycle stability.

[0133] In summary, in this invention, zinc sulfate, zinc acetate, zinc bromide, and zinc trifluoromethanesulfonate in the four zinc salt combinations each have their unique roles in synergistically stabilizing the multi-electron reaction at the iodine cathode, primarily due to the presence of SO4 in zinc sulfate. 2- Buffering the pH of the system reduces negative electrode side reactions; CH3COO in zinc acetate - Capable of crosslinking I3 - It inhibits polyiodide shuttle and enhances the reversibility of two-electron reactions; Br in zinc bromide - Through isohalogen chemical binding of I + The four-electron reaction is activated; the strongly electronegative trifluoromethanesulfonate ion OTf in zinc trifluoromethanesulfonate - By utilizing the "ion atmosphere effect", surround positively charged I + This prevents active water molecules from attacking and degrading the hydrolysis process.

[0134] Comparative Example 1

[0135] Step 1: Weigh 11.502g of zinc sulfate, add it to 15mL of water, stir until clear, transfer the solution to a volumetric flask, and make up to 20mL to obtain a 2M zinc sulfate single-combination zinc salt electrolyte.

[0136] Step 2: Iodine and activated carbon are manually ground and mixed at a mass ratio of 1:1, then heated at 180℃ for 12 hours for adsorption, and finally heated at 80℃ in an open environment for 6 hours to obtain the iodine@activated carbon composite material. The iodine@activated carbon composite material, conductive agent, and binder are uniformly mixed at a mass ratio of 8:1:1, and deionized water is added to disperse them into a slurry. This slurry is then coated onto a 5mm thick graphite felt and dried to obtain the positive electrode sheet (the amount of each raw material used in the positive electrode material is the same as in Example 1).

[0137] Step 3: Assemble zinc-iodine pouch cells using the prepared positive electrode, zinc foil, and electrolyte.

[0138] Comparative Example 2

[0139] Step 1: Weigh 8.780g of zinc acetate, add it to 15mL of water, stir until clear, transfer the solution to a volumetric flask, and make up to 20mL to obtain a 2M zinc acetate single-combination zinc salt electrolyte.

[0140] Step 2: Iodine and activated carbon are manually ground and mixed at a mass ratio of 1:1, then heated at 180℃ for 12 hours for adsorption, and finally heated at 80℃ in an open environment for 6 hours to obtain the iodine@activated carbon composite material. The iodine@activated carbon composite material, conductive agent, and binder are uniformly mixed at a mass ratio of 8:1:1, and deionized water is added to disperse them into a slurry. This slurry is then coated onto a 5mm thick graphite felt and dried to obtain the positive electrode sheet (the amount of each raw material used in the positive electrode material is the same as in Example 1).

[0141] Step 3: Assemble zinc-iodine pouch cells using the prepared positive electrode, zinc foil, and electrolyte.

[0142] Comparative Example 3

[0143] Step 1: Weigh 9.008g of zinc bromide and add it to 15mL of water. Stir until the solution is clear. Transfer the solution to a volumetric flask and make up to 20mL to obtain a 2M zinc bromide single-combination zinc salt electrolyte.

[0144] Step 2: Iodine and activated carbon are manually ground and mixed at a mass ratio of 1:1, then heated at 180℃ for 12 hours for adsorption, and finally heated at 80℃ in an open environment for 6 hours to obtain the iodine@activated carbon composite material. The iodine@activated carbon composite material, conductive agent, and binder are uniformly mixed at a mass ratio of 8:1:1, and deionized water is added to disperse them into a slurry. This slurry is then coated onto a 5mm thick graphite felt and dried to obtain the positive electrode sheet (the amount of each raw material used in the positive electrode material is the same as in Example 1).

[0145] Step 3: Assemble zinc-iodine pouch cells using the prepared positive electrode, zinc foil, and electrolyte.

[0146] Comparative Example 4

[0147] Step 1: Weigh 14.541g of zinc trifluoromethanesulfonate, add it to 15mL of water, stir until clear, transfer the solution to a volumetric flask, and make up to 20mL to obtain a 2M zinc trifluoromethanesulfonate single-combination zinc salt electrolyte.

[0148] Step 2: Iodine and activated carbon are manually ground and mixed at a mass ratio of 1:1, then heated at 180℃ for 12 hours for adsorption, and finally heated at 80℃ in an open environment for 6 hours to obtain the iodine@activated carbon composite material. The iodine@activated carbon composite material, conductive agent, and binder are uniformly mixed at a mass ratio of 8:1:1, and deionized water is added to disperse them into a slurry. This slurry is then coated onto a 5mm thick graphite felt and dried to obtain the positive electrode sheet (the amount of each raw material used in the positive electrode material is the same as in Example 1).

[0149] Step 3: Assemble zinc-iodine pouch cells using the prepared positive electrode, zinc foil, and electrolyte.

[0150] Comparative Example 5

[0151] Step 1: Weigh 5.571g of zinc sulfate and 4.390g of zinc acetate, add them together to 15mL of water, stir until clear, transfer the solution to a volumetric flask, and make up to 20mL to obtain a 1.0M zinc sulfate + 1.0M zinc acetate dual zinc salt electrolyte.

[0152] Step 2: Iodine and activated carbon are manually ground and mixed at a mass ratio of 1:1, then heated at 180℃ for 12 hours for adsorption, and finally heated at 80℃ in an open environment for 6 hours to obtain the iodine@activated carbon composite material. The iodine@activated carbon composite material, conductive agent, and binder are uniformly mixed at a mass ratio of 8:1:1, and deionized water is added to disperse them into a slurry. This slurry is then coated onto a 5mm thick graphite felt and dried to obtain the positive electrode sheet (the amount of each raw material used in the positive electrode material is the same as in Example 1).

[0153] Step 3: Assemble zinc-iodine pouch cells using the prepared positive electrode, zinc foil, and electrolyte.

[0154] Comparative Example 6

[0155] Step 1: Weigh 5.571g of zinc sulfate and 4.504g of zinc bromide, add them together to 15mL of water, stir until clear, transfer the solution to a volumetric flask, and make up to 20mL to obtain a 1.0M zinc sulfate + 1.0M zinc bromide dual zinc salt electrolyte.

[0156] Step 2: Iodine and activated carbon are manually ground and mixed at a mass ratio of 1:1, then heated at 180℃ for 12 hours for adsorption, and finally heated at 80℃ in an open environment for 6 hours to obtain the iodine@activated carbon composite material. The iodine@activated carbon composite material, conductive agent, and binder are uniformly mixed at a mass ratio of 8:1:1, and deionized water is added to disperse them into a slurry. This slurry is then coated onto a 5mm thick graphite felt and dried to obtain the positive electrode sheet (the amount of each raw material used in the positive electrode material is the same as in Example 1).

[0157] Step 3: Assemble zinc-iodine pouch cells using the prepared positive electrode, zinc foil, and electrolyte.

[0158] Comparative Example 7

[0159] Step 1: Weigh 5.571g of zinc sulfate and 7.271g of zinc trifluoromethanesulfonate, add them together to 15mL of water, stir until clear, transfer the solution to a volumetric flask, and make up to 20mL to obtain a 1.0M zinc sulfate + 1.0M zinc trifluoromethanesulfonate dual zinc salt electrolyte.

[0160] Step 2: Iodine and activated carbon are manually ground and mixed at a mass ratio of 1:1, then heated at 180℃ for 12 hours for adsorption, and finally heated at 80℃ in an open environment for 6 hours to obtain the iodine@activated carbon composite material. The iodine@activated carbon composite material, conductive agent, and binder are uniformly mixed at a mass ratio of 8:1:1, and deionized water is added to disperse them into a slurry. This slurry is then coated onto a 5mm thick graphite felt and dried to obtain the positive electrode sheet (the amount of each raw material used in the positive electrode material is the same as in Example 1).

[0161] Step 3: Assemble zinc-iodine pouch cells using the prepared positive electrode, zinc foil, and electrolyte.

[0162] Comparative Example 8

[0163] Step 1: Weigh 4.390g of zinc acetate and 4.504g of zinc bromide, add them together to 15mL of water, stir until clear, transfer the solution to a volumetric flask, and make up to 20mL to obtain a 1.0M zinc acetate + 1.0M zinc bromide dual zinc salt electrolyte.

[0164] Step 2: Iodine and activated carbon are manually ground and mixed at a mass ratio of 1:1, then heated at 180℃ for 12 hours for adsorption, and finally heated at 80℃ in an open environment for 6 hours to obtain the iodine@activated carbon composite material. The iodine@activated carbon composite material, conductive agent, and binder are uniformly mixed at a mass ratio of 8:1:1, and deionized water is added to disperse them into a slurry. This slurry is then coated onto a 5mm thick graphite felt and dried to obtain the positive electrode sheet (the amount of each raw material used in the positive electrode material is the same as in Example 1).

[0165] Step 3: Assemble zinc-iodine pouch cells using the prepared positive electrode, zinc foil, and electrolyte.

[0166] Comparative Example 9

[0167] Step 1: Weigh 4.390g of zinc acetate and 7.271g of zinc trifluoromethanesulfonate, add them together to 15mL of water, stir until clear, transfer the solution to a volumetric flask, and make up to 20mL to obtain a 1.0M zinc acetate + 1.0M zinc trifluoromethanesulfonate dual zinc salt electrolyte.

[0168] Step 2: Iodine and activated carbon are manually ground and mixed at a mass ratio of 1:1, then heated at 180℃ for 12 hours for adsorption, and finally heated at 80℃ in an open environment for 6 hours to obtain the iodine@activated carbon composite material. The iodine@activated carbon composite material, conductive agent, and binder are uniformly mixed at a mass ratio of 8:1:1, and deionized water is added to disperse them into a slurry. This slurry is then coated onto a 5mm thick graphite felt and dried to obtain the positive electrode sheet (the amount of each raw material used in the positive electrode material is the same as in Example 1).

[0169] Step 3: Assemble zinc-iodine pouch cells using the prepared positive electrode, zinc foil, and electrolyte.

[0170] Comparative Example 10

[0171] Step 1: Weigh 4.504g of zinc bromide and 7.271g of zinc trifluoromethanesulfonate, add them together to 15mL of water, stir until clear, transfer the solution to a volumetric flask, and make up to 20mL to obtain a 1.0M zinc bromide + 1.0M zinc trifluoromethanesulfonate dual zinc salt electrolyte.

[0172] Step 2: Iodine and activated carbon are manually ground and mixed at a mass ratio of 1:1, then heated at 180℃ for 12 hours for adsorption, and finally heated at 80℃ in an open environment for 6 hours to obtain the iodine@activated carbon composite material. The iodine@activated carbon composite material, conductive agent, and binder are uniformly mixed at a mass ratio of 8:1:1, and deionized water is added to disperse them into a slurry. This slurry is then coated onto a 5mm thick graphite felt and dried to obtain the positive electrode sheet (the amount of each raw material used in the positive electrode material is the same as in Example 1).

[0173] Step 3: Assemble zinc-iodine pouch cells using the prepared positive electrode, zinc foil, and electrolyte.

[0174] Comparative Example 11

[0175] Step 1: Weigh 3.796g zinc sulfate, 2.897g zinc acetate, and 2.972g zinc bromide, add them together to 15mL of water, stir until clear, transfer the solution to a volumetric flask, and make up to 20mL to obtain a three-combination zinc salt electrolyte of 0.66M zinc sulfate + 0.66M zinc acetate + 0.66M zinc bromide.

[0176] Step 2: Iodine and activated carbon are manually ground and mixed at a mass ratio of 1:1, then heated at 180℃ for 12 hours for adsorption, and finally heated at 80℃ in an open environment for 6 hours to obtain the iodine@activated carbon composite material. The iodine@activated carbon composite material, conductive agent, and binder are uniformly mixed at a mass ratio of 8:1:1, and deionized water is added to disperse them into a slurry. This slurry is then coated onto a 5mm thick graphite felt and dried to obtain the positive electrode sheet (the amount of each raw material used in the positive electrode material is the same as in Example 1).

[0177] Step 3: Assemble zinc-iodine pouch cells using the prepared positive electrode, zinc foil, and electrolyte.

[0178] Comparative Example 12

[0179] Step 1: Weigh 3.796g zinc sulfate, 2.897g zinc acetate, and 4.799g zinc trifluoromethanesulfonate, add them together to 15mL of water, stir until clear, transfer the solution to a volumetric flask, and make up to 20mL to obtain a three-combination zinc salt electrolyte of 0.66M zinc sulfate + 0.66M zinc acetate + 0.66M zinc trifluoromethanesulfonate.

[0180] Step 2: Iodine and activated carbon are manually ground and mixed at a mass ratio of 1:1, then heated at 180℃ for 12 hours for adsorption, and finally heated at 80℃ in an open environment for 6 hours to obtain the iodine@activated carbon composite material. The iodine@activated carbon composite material, conductive agent, and binder are uniformly mixed at a mass ratio of 8:1:1, and deionized water is added to disperse them into a slurry. This slurry is then coated onto a 5mm thick graphite felt and dried to obtain the positive electrode sheet (the amount of each raw material used in the positive electrode material is the same as in Example 1).

[0181] Step 3: Assemble zinc-iodine pouch cells using the prepared positive electrode, zinc foil, and electrolyte.

[0182] Comparative Example 13

[0183] Step 1: Weigh 3.796g zinc sulfate, 2.972g zinc bromide, and 4.799g zinc trifluoromethanesulfonate, add them together to 15mL of water, stir until clear, transfer the solution to a volumetric flask, and make up to 20mL to obtain a three-combination zinc salt electrolyte of 0.66M zinc sulfate + 0.66M zinc bromide + 0.66M zinc trifluoromethanesulfonate.

[0184] Step 2: Iodine and activated carbon are manually ground and mixed at a mass ratio of 1:1, then heated at 180℃ for 12 hours for adsorption, and finally heated at 80℃ in an open environment for 6 hours to obtain the iodine@activated carbon composite material. The iodine@activated carbon composite material, conductive agent, and binder are uniformly mixed at a mass ratio of 8:1:1, and deionized water is added to disperse them into a slurry. This slurry is then coated onto a 5mm thick graphite felt and dried to obtain the positive electrode sheet (the amount of each raw material used in the positive electrode material is the same as in Example 1).

[0185] Step 3: Assemble zinc-iodine pouch cells using the prepared positive electrode, zinc foil, and electrolyte.

[0186] Comparative Example 14

[0187] Step 1: Weigh 2.897g zinc acetate, 2.972g zinc bromide, and 4.799g zinc trifluoromethanesulfonate, add them together to 15mL of water, stir until clear, transfer the solution to a volumetric flask, and make up to 20mL to obtain a three-combination zinc salt electrolyte of 0.66M zinc acetate + 0.66M zinc bromide + 0.66M zinc trifluoromethanesulfonate.

[0188] Step 2: Iodine and activated carbon are manually ground and mixed at a mass ratio of 1:1, then heated at 180℃ for 12 hours for adsorption, and finally heated at 80℃ in an open environment for 6 hours to obtain the iodine@activated carbon composite material. The iodine@activated carbon composite material, conductive agent, and binder are uniformly mixed at a mass ratio of 8:1:1, and deionized water is added to disperse them into a slurry. This slurry is then coated onto a 5mm thick graphite felt and dried to obtain the positive electrode sheet (the amount of each raw material used in the positive electrode material is the same as in Example 1).

[0189] Step 3: Assemble zinc-iodine pouch cells using the prepared positive electrode, zinc foil, and electrolyte.

[0190] Comparative Example 15

[0191] Step 1: Weigh 4.026g zinc sulfate, 1.317g zinc acetate, 2.252g zinc bromide, and 2.181g zinc trifluoromethanesulfonate, add them together to 15mL of water, stir until clear, transfer the solution to a volumetric flask, and make up to 20mL to obtain a four-component zinc salt electrolyte consisting of 0.7M zinc sulfate + 0.3M zinc acetate + 0.5M zinc bromide + 0.3M zinc trifluoromethanesulfonate.

[0192] Step 2: Iodine and activated carbon are manually ground and mixed at a mass ratio of 1:1, then heated at 180℃ for 12 hours for adsorption, and finally heated at 80℃ in an open environment for 6 hours to obtain the iodine@activated carbon composite material. The iodine@activated carbon composite material, conductive agent, and binder are uniformly mixed at a mass ratio of 8:1:1, and deionized water is added to disperse them into a slurry. This slurry is then coated onto a 5mm thick graphite felt and dried to obtain the positive electrode sheet (the amount of each raw material used in the positive electrode material is the same as in Example 1).

[0193] Step 3: Assemble zinc-iodine pouch cells using the prepared positive electrode, zinc foil, and electrolyte.

[0194] Comparative Example 16

[0195] Step 1: Weigh 6.326g zinc sulfate, 1.317g zinc acetate, 2.252g zinc bromide, and 2.181g zinc trifluoromethanesulfonate, add them together to 15mL of water, stir until clear, transfer the solution to a volumetric flask, and make up to 20mL to obtain a four-component zinc salt electrolyte consisting of 1.1M zinc sulfate + 0.3M zinc acetate + 0.5M zinc bromide + 0.3M zinc trifluoromethanesulfonate.

[0196] Step 2: Iodine and activated carbon are manually ground and mixed at a mass ratio of 1:1, then heated at 180℃ for 12 hours for adsorption, and finally heated at 80℃ in an open environment for 6 hours to obtain the iodine@activated carbon composite material. The iodine@activated carbon composite material, conductive agent, and binder are uniformly mixed at a mass ratio of 8:1:1, and deionized water is added to disperse them into a slurry. This slurry is then coated onto a 5mm thick graphite felt and dried to obtain the positive electrode sheet (the amount of each raw material used in the positive electrode material is the same as in Example 1).

[0197] Step 3: Assemble zinc-iodine pouch cells using the prepared positive electrode, zinc foil, and electrolyte.

[0198] Comparative Example 17

[0199] Step 1: Weigh 5.176g zinc sulfate, 0.439g zinc acetate, 2.252g zinc bromide, and 2.181g zinc trifluoromethanesulfonate, add them together to 15mL of water, stir until clear, transfer the solution to a volumetric flask, and make up to 20mL to obtain a four-component zinc salt electrolyte consisting of 0.9M zinc sulfate + 0.1M zinc acetate + 0.5M zinc bromide + 0.3M zinc trifluoromethanesulfonate.

[0200] Step 2: Iodine and activated carbon are manually ground and mixed at a mass ratio of 1:1, then heated at 180℃ for 12 hours for adsorption, and finally heated at 80℃ in an open environment for 6 hours to obtain the iodine@activated carbon composite material. The iodine@activated carbon composite material, conductive agent, and binder are uniformly mixed at a mass ratio of 8:1:1, and deionized water is added to disperse them into a slurry. This slurry is then coated onto a 5mm thick graphite felt and dried to obtain the positive electrode sheet (the amount of each raw material used in the positive electrode material is the same as in Example 1).

[0201] Step 3: Assemble zinc-iodine pouch cells using the prepared positive electrode, zinc foil, and electrolyte.

[0202] Comparative Example 18

[0203] Step 1: Weigh 5.176g zinc sulfate, 2.195g zinc acetate, 2.252g zinc bromide, and 2.181g zinc trifluoromethanesulfonate, add them together to 15mL of water, stir until clear, transfer the solution to a volumetric flask, and make up to 20mL to obtain a four-component zinc salt electrolyte consisting of 0.9M zinc sulfate + 0.5M zinc acetate + 0.5M zinc bromide + 0.3M zinc trifluoromethanesulfonate.

[0204] Step 2: Iodine and activated carbon are manually ground and mixed at a mass ratio of 1:1, then heated at 180℃ for 12 hours for adsorption, and finally heated at 80℃ in an open environment for 6 hours to obtain the iodine@activated carbon composite material. The iodine@activated carbon composite material, conductive agent, and binder are uniformly mixed at a mass ratio of 8:1:1, and deionized water is added to disperse them into a slurry. This slurry is then coated onto a 5mm thick graphite felt and dried to obtain the positive electrode sheet (the amount of each raw material used in the positive electrode material is the same as in Example 1).

[0205] Step 3: Assemble zinc-iodine pouch cells using the prepared positive electrode, zinc foil, and electrolyte.

[0206] Comparative Example 19

[0207] Step 1: Weigh 5.176g zinc sulfate, 1.317g zinc acetate, 1.351g zinc bromide, and 2.181g zinc trifluoromethanesulfonate, add them together to 15mL of water, stir until clear, transfer the solution to a volumetric flask, and make up to 20mL to obtain a four-component zinc salt electrolyte consisting of 0.9M zinc sulfate + 0.3M zinc acetate + 0.3M zinc bromide + 0.3M zinc trifluoromethanesulfonate.

[0208] Step 2: Iodine and activated carbon are manually ground and mixed at a mass ratio of 1:1, then heated at 180℃ for 12 hours for adsorption, and finally heated at 80℃ in an open environment for 6 hours to obtain the iodine@activated carbon composite material. The iodine@activated carbon composite material, conductive agent, and binder are uniformly mixed at a mass ratio of 8:1:1, and deionized water is added to disperse them into a slurry. This slurry is then coated onto a 5mm thick graphite felt and dried to obtain the positive electrode sheet (the amount of each raw material used in the positive electrode material is the same as in Example 1).

[0209] Step 3: Assemble zinc-iodine pouch cells using the prepared positive electrode, zinc foil, and electrolyte.

[0210] Comparative Example 20

[0211] Step 1: Weigh 5.176g zinc sulfate, 1.317g zinc acetate, 3.153g zinc bromide, and 2.181g zinc trifluoromethanesulfonate, add them together to 15mL of water, stir until clear, transfer the solution to a volumetric flask, and make up to 20mL to obtain a four-component zinc salt electrolyte consisting of 0.9M zinc sulfate + 0.3M zinc acetate + 0.7M zinc bromide + 0.3M zinc trifluoromethanesulfonate.

[0212] Step 2: Iodine and activated carbon are manually ground and mixed at a mass ratio of 1:1, then heated at 180℃ for 12 hours for adsorption, and finally heated at 80℃ in an open environment for 6 hours to obtain the iodine@activated carbon composite material. The iodine@activated carbon composite material, conductive agent, and binder are uniformly mixed at a mass ratio of 8:1:1, and deionized water is added to disperse them into a slurry. This slurry is then coated onto a 5mm thick graphite felt and dried to obtain the positive electrode sheet (the amount of each raw material used in the positive electrode material is the same as in Example 1).

[0213] Step 3: Assemble zinc-iodine pouch cells using the prepared positive electrode, zinc foil, and electrolyte.

[0214] Comparative Example 21

[0215] Step 1: Weigh 5.176g zinc sulfate, 1.317g zinc acetate, 2.252g zinc bromide, and 0.727g zinc trifluoromethanesulfonate, add them together to 15mL of water, stir until clear, transfer the solution to a volumetric flask, and make up to 20mL to obtain a four-component zinc salt electrolyte consisting of 0.9M zinc sulfate + 0.3M zinc acetate + 0.5M zinc bromide + 0.1M zinc trifluoromethanesulfonate.

[0216] Step 2: Iodine and activated carbon are manually ground and mixed at a mass ratio of 1:1, then heated at 180℃ for 12 hours for adsorption, and finally heated at 80℃ in an open environment for 6 hours to obtain the iodine@activated carbon composite material. The iodine@activated carbon composite material, conductive agent, and binder are uniformly mixed at a mass ratio of 8:1:1, and deionized water is added to disperse them into a slurry. This slurry is then coated onto a 5mm thick graphite felt and dried to obtain the positive electrode sheet (the amount of each raw material used in the positive electrode material is the same as in Example 1).

[0217] Step 3: Assemble zinc-iodine pouch cells using the prepared positive electrode, zinc foil, and electrolyte.

[0218] Comparative Example 22

[0219] Step 1: Weigh 5.176g zinc sulfate, 1.317g zinc acetate, 2.252g zinc bromide, and 3.635g zinc trifluoromethanesulfonate, add them together to 15mL of water, stir until clear, transfer the solution to a volumetric flask, and make up to 20mL to obtain a four-component zinc salt electrolyte consisting of 0.9M zinc sulfate + 0.3M zinc acetate + 0.5M zinc bromide + 0.5M zinc trifluoromethanesulfonate.

[0220] Step 2: Iodine and activated carbon are manually ground and mixed at a mass ratio of 1:1, then heated at 180℃ for 12 hours for adsorption, and finally heated at 80℃ in an open environment for 6 hours to obtain the iodine@activated carbon composite material. The iodine@activated carbon composite material, conductive agent, and binder are uniformly mixed at a mass ratio of 8:1:1, and deionized water is added to disperse them into a slurry. This slurry is then coated onto a 5mm thick graphite felt and dried to obtain the positive electrode sheet (the amount of each raw material used in the positive electrode material is the same as in Example 1).

[0221] Step 3: Assemble zinc-iodine pouch cells using the prepared positive electrode, zinc foil, and electrolyte.

[0222] Table 2 presents a statistical table of the performance of zinc-iodine pouch batteries using all comparative electrolytes of this invention. As can be seen from the table, all comparative examples exhibit one or more problems, including low specific capacity, low coulombic efficiency, low areal capacity, and insufficient cycle stability. This indicates that none of the comparative examples can simultaneously stabilize the two-electron and four-electron reactions of the positive electrode iodine, i.e., suppress the polyiodide shuttle effect and I... + Hydrolysis problem.

[0223] Table 2. Performance of zinc-iodine pouch cells using comparative electrolytes in this invention

[0224]

[0225] Finally, it should be noted that the terms “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0226] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention.

[0227] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. An electrolyte for synergistic stabilization of the positive electrode iodine multi-electron reaction by a combination of four zinc salts, characterized in that, The electrolyte contains four combinations of zinc salts and water; In the electrolyte, the total zinc ion concentration of the four zinc salt combinations is 2 ± 0.2 mol / L.

2. The electrolyte for synergistic stabilization of the positive electrode iodine multi-electron reaction by a four-combination zinc salt according to claim 1, characterized in that, The four zinc salts are zinc sulfate, zinc acetate, zinc bromide, and zinc trifluoromethanesulfonate, with a molar ratio of (0.8-1.0):(0.2-0.4):(0.4-0.6):(0.2-0.4).

3. The method for preparing an electrolyte for synergistic stabilization of the positive electrode iodine multi-electron reaction by four zinc salt combinations according to claim 1 or 2, characterized in that, The preparation method includes: Four zinc salts were dissolved in water and then magnetically stirred to obtain an electrolyte in which the four zinc salts synergistically stabilized the positive electrode iodine multi-electron reaction.

4. The application of the electrolyte described in claim 1 or 2, which synergistically stabilizes the positive electrode iodine multi-electron reaction with a four-combination zinc salt, in the preparation of a four-electron zinc-iodine soft-pack battery.

5. A zinc-iodine soft-pack battery, characterized in that, The zinc-iodine soft-pack battery contains an electrolyte as described in claim 1 or 2, which uses a four-combination zinc salt to synergistically stabilize the positive electrode iodine multi-electron reaction.

6. A zinc-iodine soft-pack battery, characterized in that, The zinc-iodine soft-pack battery uses iodine@carbon composite material as the positive electrode, metallic zinc as the negative electrode, glass fiber membrane as the separator, and an electrolyte as described in claim 1 or 2, which uses a four-combination zinc salt synergistically to stabilize the positive electrode iodine multi-electron reaction.

7. A zinc-iodine soft-pack battery according to claim 6, characterized in that, The carbon in the iodine@carbon composite material is activated carbon with adsorption properties.

8. A method for preparing a zinc-iodine soft-pack battery according to claim 6 or 7, characterized in that, Assemble the assembly in the following order: (1) Preparation of the positive electrode sheet: S1. Grind and mix iodine and carbon, then heat at 150-200℃ for adsorption; S2. After adsorption is complete, heat at 60-100℃ in an open environment to obtain iodine@carbon composite material; S3. Mix the above-mentioned iodine@carbon composite material, conductive agent and binder in a uniform ratio, and add deionized water to disperse and form a slurry; S4. Apply the above slurry onto graphite felt and dry it to obtain the positive electrode sheet. (2) Cut the above positive electrode sheet, negative electrode zinc foil and separator; (3) The separator and the prepared positive electrode sheet are wetted with electrolyte, and then the positive electrode sheet and the negative zinc foil are separated by the separator. The battery is placed in an aluminum-plastic film bag and sealed to obtain a four-electron zinc-iodine soft pack battery.

9. The method for preparing a zinc-iodine soft-pack battery according to claim 8, characterized in that, The areal loading of iodine in the positive electrode is 30 mg / cm³. -2 ; And / or, the conductive agent is Ketjen Black; the binder is sodium carboxymethyl cellulose; and the diaphragm is a glass fiber diaphragm.

10. The method for preparing a zinc-iodine soft-pack battery according to claim 8, characterized in that, The mass ratio of iodine to carbon in S1 is 1:(0.5-2). And / or, the adsorption conditions in S1 are adsorption by heating at 180°C for 12 hours; And / or, the heating conditions in S2 are heating at 80°C in an open environment for 6 hours; And / or, the iodine@carbon composite material, conductive agent, and binder in S3 are uniformly mixed in a mass ratio of 8:1:1; And / or, the thickness of the graphite felt in S4 is 5 mm; And / or, in step (2), the positive electrode sheet is cut to a size of 4*5cm, the negative electrode zinc foil is cut to a size of 4.5*5.5cm, and the separator is cut to a size of 5*6cm.

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