A method for preparing an aqueous zinc-ion gel electrolyte and an aqueous zinc-ion battery

Abstract

This invention discloses a method for preparing an aqueous zinc-ion gel electrolyte and an aqueous zinc-ion battery, belonging to the technical field of aqueous zinc-ion batteries. The preparation method includes the following steps: dispersing an ionic liquid in a homogeneous aqueous solution of Tween 80, adding a polyphenolic compound, and ultrasonically forming a dispersion containing nano-sized oil droplets; then adding acrylamide and zinc salt and mixing thoroughly; subsequently adding N,N'-methylenebisacrylamide and ammonium persulfate and stirring until homogeneous, followed by a polymerization reaction to obtain the aqueous zinc-ion gel electrolyte. The hydrogel electrolyte prepared by this invention achieves a systematic improvement in the performance of aqueous zinc-iodine battery gel electrolytes, and the resulting electrolyte exhibits excellent tensile and cycling properties. Aqueous zinc-ion batteries assembled using this electrolyte exhibit excellent cycle stability and cycle discharge performance. This preparation process is simple, the raw materials are readily available, and it is suitable for large-scale production, showing broad market application prospects in the fields of zinc-ion batteries and zinc-ion energy storage devices.

Description

Technical Field

[0001] This invention relates to the field of aqueous zinc-ion battery technology, specifically to a method for preparing an aqueous zinc-ion gel electrolyte and an aqueous zinc-ion battery. Background Technology

[0002] Among various energy storage devices, aqueous zinc-ion batteries are widely regarded as strong candidates for next-generation energy storage devices due to their ultra-high theoretical capacity (820 mAh g⁻¹), low redox potential (-0.76 V vs. SHE), and inherent safety of the aqueous system. Meanwhile, aqueous zinc-iodine batteries, as an important branch of aqueous zinc-based batteries, also represent a promising next-generation energy storage system, leveraging the inherent safety of non-flammable aqueous electrolytes, the low-cost raw material advantage from abundant zinc and iodine resources, and high theoretical capacity. However, the commercialization of aqueous zinc-iodine batteries still faces many severe challenges: on the positive electrode side, water-soluble polyiodide intermediates are prone to dissolution and diffusion, leading to a significant loss of active materials and rapid capacity decay; the slow redox kinetics of iodine severely limit the rate performance and power density of the battery; on the negative electrode side, uncontrollable dendrite growth and side reactions (such as hydrogen evolution reaction) easily occur in the zinc electrode during charging and discharging, significantly damaging the battery's cycle stability. Therefore, overcoming the aforementioned key technological bottlenecks is the core prerequisite and key to promoting the transformation of aqueous zinc-iodine batteries from basic laboratory research to practical industrial applications.

[0003] Currently, to effectively suppress the shuttle effect of polyiodides in aqueous zinc-iodine batteries and improve battery cycle stability and energy utilization efficiency, researchers are focusing their efforts on several key areas, including electrolyte modification, separator modification, screening of novel iodine host materials, and development of functionalized adhesives. Among these, electrolyte modification, as one of the core methods for suppressing polyiodide shuttle, has seen the exploration of various technical pathways. For example, "water-in-salt" electrolytes are widely used to suppress the polyiodide shuttle effect, achieving high coulombic efficiency in batteries. However, excessively high electrolyte concentrations significantly increase system viscosity, hindering rapid ion transport and thus affecting battery rate performance.

[0004] Therefore, there is an urgent need to develop a novel electrolyte system that can synergistically suppress the polyiodide shuttle structure at the molecular level and construct a high-performance system. Summary of the Invention

[0005] The present invention aims to solve the technical problem that the existing strategy for suppressing polyiodide shuttle is difficult to balance the reversibility of the positive electrode, excellent mechanical properties and durability, and provides a method for preparing an aqueous zinc ion gel electrolyte and an aqueous zinc ion battery.

[0006] The "liquid-phase encapsulation compartmentalized phase separation" described in this invention refers to the confinement of ionic liquids in the form of nanodroplets within a polymer network, forming a microscopic phase separation structure to achieve compartmentalized encapsulation of active substances.

[0007] To achieve the above objectives, in a first aspect, the present invention provides a method for preparing an aqueous zinc ion gel electrolyte, comprising the following steps:

[0008] (1) The bis(trifluoromethanesulfonyl)imine salt ionic liquid with the general formula [X][TFSI] is dispersed in a homogeneous aqueous solution formed by Tween 80, and then a polyphenolic compound is added. The dispersion containing nano-sized oil phase droplets is formed by ultrasonication.

[0009] In the general formula [X][TFSI], [X] represents the cation portion and [TFSI] represents the anion portion; wherein [X] is a cation capable of forming an ionic liquid with the bis(trifluoromethanesulfonyl)imide anion, and [TFSI] is the bis(trifluoromethanesulfonyl)imide anion;

[0010] (2) Add acrylamide, zinc salt, N,N'-methylenebisacrylamide and ammonium persulfate to the dispersion in step (1) and stir until uniform to obtain a mixture; pour the mixture into a mold and obtain an aqueous zinc ion gel electrolyte based on bis(trifluoromethanesulfonyl)imide ionic liquid liquid phase encapsulation compartment phase separation through polymerization reaction.

[0011] As a further preferred embodiment of the present invention, [X] is one of 1-ethyl-3-methylimidazolium cation, tributylmethylammonium cation, methyltributylphosphonium cation, 1-butyl-1-methylpyrrolidine cation, and N-butylpyridine cation.

[0012] As a further preferred embodiment of the present invention, the polyphenolic compound is at least one of hydroquinone, resorcinol, catechol, and phloroglucinol.

[0013] As a further preferred embodiment of the present invention, the zinc salt is at least one of zinc sulfate, zinc chloride, zinc perchlorate, zinc trifluoromethanesulfonate, and zinc bis(trifluoromethanesulfonyl)imide.

[0014] As a further preferred embodiment of the present invention, the mixture contains: 1-5 wt% bis(trifluoromethanesulfonyl)imine ionic liquid; 1-2 wt% Tween 80; 0.4-0.8 wt% polyphenolic compounds; 15-20 wt% acrylamide; 0.01-0.1 wt% N,N'-methylenebisacrylamide; 0.01-0.1 wt% ammonium persulfate; and a zinc salt concentration of 1-4 mol / L.

[0015] As a further preferred embodiment of the present invention, the mixture contains 2.5 wt% bis(trifluoromethanesulfonyl)imine ionic liquid; 1 wt% Tween 80; 0.6 wt% polyphenolic compounds; 20 wt% acrylamide; 2 mol / L zinc salt; 0.05 wt% N,N'-methylenebisacrylamide; and 0.05 wt% ammonium persulfate.

[0016] As a further preferred technical solution of the present invention, step (1) specifically includes: first adding Tween 80 to deionized water and dispersing it by ultrasonication, then adding bis(trifluoromethanesulfonyl)imine salt ionic liquid and continuing to disperse it by ultrasonication, and finally adding polyphenolic compounds and dispersing them by ultrasonication.

[0017] As a further preferred embodiment of the present invention, the polymerization reaction is carried out at 60~80 °C under static conditions.

[0018] According to a second aspect of the present invention, the present invention also provides an aqueous zinc ion gel electrolyte, which is prepared by the above-described preparation method. Specifically, the aqueous zinc ion gel electrolyte comprises an aqueous solution of zinc salt, wherein a bis(trifluoromethanesulfonyl)imide salt ionic liquid additive having the general formula [X][TFSI] and a polyphenolic compound are added as structural stabilizers and reducing agents.

[0019] According to a third aspect of the present invention, the present invention also provides an aqueous zinc-ion battery comprising the above-described aqueous zinc-ion gel electrolyte.

[0020] The principle of this invention is as follows: A stable nano-oil phase droplet is formed by a bis(trifluoromethanesulfonyl)imide anionic ionic liquid and Tween 80. Then, with the participation of polyphenolic compounds, the interaction between the droplet micro-regions and the polymer matrix and zinc anode interface is regulated. Finally, the droplet micro-regions are fixed within the gel network through in-situ polymerization, thereby constructing a composite gel electrolyte structure with compartmentalized phase separation characteristics. In this aqueous zinc ion gel electrolyte, the dispersed micro-regions formed by the ionic liquid / Tween 80 are fixed within the continuous polymer phase as nano-confined regions. The polymer molecular chain entanglement and cross-linking network confine and stabilize these micro-regions, forming a multi-scale composite structure that combines ion transport channels, active species confinement regions, and interface stability. The added polyphenolic compounds are not ordinary plasticizers or additives, but key components used to synergistically regulate the stability of the micro-regions within the gel and the stability of the zinc anode interface. The inventors have found that the introduction of polyphenolic compounds not only enhances the interaction between the ionic liquid micro-regions and the polymer network, but also improves the stability of the Zn nano-oil phase droplet interface outside the compartmentalized phase. 2+ The polyiodide in the transmission channel has a reducing effect and is conducive to the formation of a more stable interface protective layer on the zinc anode surface, thereby reducing the risk of corrosion side reactions and dendrite growth.

[0021] Compared with the prior art, the present invention can achieve the following beneficial effects:

[0022] (1) This invention constructs a composite gel microstructure with compartmentalized phase separation characteristics by fixing nano-oil phase droplets formed by bis(trifluoromethanesulfonyl)imide ionic liquid and Tween 80 into a continuous polymer phase. This structure facilitates rapid ion transport and confines the diffusion of active iodine species. Simultaneously, the introduction of polyphenolic compounds further enhances the internal interactions of the gel and the stability of the zinc anode interface, thus improving the Zn content outside the compartments formed by the nano-oil phase droplets. 2+ The polyiodide in the transmission channel has a reducing effect, so that the resulting gel electrolyte not only exhibits the general effect of "good flexibility and water retention", but also has superior mechanical properties, lower corrosion current density, longer zinc-zinc symmetric cell cycle life and excellent cycle stability such as zinc-iodine full cell.

[0023] (2) The aqueous zinc-ion battery assembled using the aqueous zinc-ion battery gel electrolyte of this invention has excellent cycle stability and cycle discharge performance. Moreover, the preparation process of the aqueous zinc-ion battery gel electrolyte is simple, the raw materials are easy to obtain, and it is suitable for large-scale production, and has broad market application prospects in the fields of zinc-ion batteries and zinc-ion energy storage devices.

[0024] (3) The zinc-zinc symmetric battery prepared by the present invention using an aqueous zinc-ion battery gel electrolyte has excellent cycle stability, such as the assembled 35 cm 2 The pouch cell can reach 1 mA cm -2 It cycles for over 1500 h at current density and exhibits excellent rate performance; the zinc-iodine full cell assembled using the aqueous zinc ion gel electrolyte also demonstrates excellent cycle stability, such as at 1 A g. -1 At current density, the capacity retention rate is still 91.0% after 9500 cycles. Attached Figure Description

[0025] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0026] Figure 1 The images show the scanning electrochemical microscopy morphology of the aqueous zinc ion gel electrolytes after freeze-drying in Comparative Examples 1, 2, 3, and 2. Figure 1 a, b, c, and d represent the gel electrolyte morphologies corresponding to Comparative Example 1, Comparative Example 2, Comparative Example 3, and Example 2, respectively.

[0027] Figure 2 The tensile stress curves of the aqueous zinc ion gel electrolytes in Comparative Example 1, Comparative Example 2, and Example 2 are shown.

[0028] Figure 3 Tafel curves of zinc-zinc symmetric batteries assembled with aqueous zinc-ion gel electrolytes in Comparative Examples 1, 2, and 2;

[0029] Figure 4 The 5×7 cm aqueous zinc ion gel electrolyte assembly used in Comparative Example 1, Comparative Example 2, Example 1, Example 2, Example 3, and Example 4 is shown. 2 Soft-pack zinc-zinc symmetric cells at 1 mA cm -2 Current density and 1 mAh cm -2 Cyclic performance test results under area capacity;

[0030] Figure 5 The 5×7cm aqueous zinc ion gel electrolyte assembled in Comparative Examples 1, 2, and 2 of this invention is an example of this invention. 2 Cyclic performance test results of soft-pack zinc-zinc symmetric cells at different current densities;

[0031] Figure 6 The zinc-zinc symmetric cells assembled with aqueous zinc-ion gel electrolytes in Comparative Examples 1, 2, and 2 of this invention were used at 1 mA cm⁻¹. -2 Current density and 1 mAh cm -2 Scanning electron microscope (SEM) images of the zinc anode after 50 cycles at the area capacity; where a, b, and c are the zinc anode morphologies corresponding to Comparative Example 1, Comparative Example 2, and Example 2, respectively.

[0032] Figure 7 The CV curves of zinc-iodine batteries assembled with aqueous zinc-ion gel electrolytes in Comparative Examples 1 and 2 of the present invention are shown at different scan rates, where a and b correspond to Comparative Examples 1 and 2, respectively.

[0033] Figure 8 For comparative examples 1 and 2, the zinc-iodine full cells assembled with aqueous zinc-ion gel electrolytes were tested at 0.2 A g. -1 Lower self-discharge curve;

[0034] Figure 9 For the zinc-iodine full cells assembled with aqueous zinc-ion gel electrolytes in Comparative Example 1 and Example 2, at 1 A g -1 Long-cycle performance graph;

[0035] Figure 10 The zinc-iodine full cell assembled with the aqueous zinc-ion gel electrolyte in Example 2 was tested at 1 A g. -1 Constant current charge-discharge curves corresponding to different number of cycles;

[0036] Figure 11The graph shows the capacity-efficiency curves of the zinc-iodine full cell assembled with the aqueous zinc ion gel electrolyte in Example 2 at different current densities.

[0037] The objectives, features, and advantages of this invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0038] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0039] Unless otherwise defined, the technical terms used in the following embodiments have the same meanings as commonly understood by those skilled in the art to which this invention pertains. Unless otherwise specified, the experimental reagents used in the following embodiments are conventional biochemical reagents; and the experimental methods described are conventional methods.

[0040] Example 1

[0041] The phase-separated aqueous zinc ion gel electrolyte provided in this embodiment is prepared through the following steps:

[0042] (1): At room temperature, 0.4 g of Tween 80 was added to 10 mL of deionized water and ultrasonically dispersed. Then, 1 g of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide was added and ultrasonically dispersed until uniform, resulting in a dispersion containing nano-sized oil droplets. Then, 0.12 g of phloroglucinol was added and ultrasonically dispersed at room temperature until it was completely dissolved, forming a uniform solution A.

[0043] (2) Add 4 g of acrylamide, 5.7 g of zinc sulfate, 0.01 g of N,N'-methylenebisacrylamide and 0.01 g of ammonium persulfate to solution A and stir until dissolved at room temperature to obtain solution B. Add solution B to a mold and let it stand at 80°C for polymerization until a transparent gel electrolyte is formed.

[0044] Example 2

[0045] The difference from Example 1 is that in the preparation step (1) of the hydrogel electrolyte, 0.4 g of Tween 80 is replaced with 0.2 g, and 1 g of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide is replaced with 0.5 g, in order to investigate the effect of the ratio of surfactant to ionic liquid on the formation of phase separation structure. The remaining steps are the same as in Example 1.

[0046] Example 3

[0047] The difference from Example 1 is that in the preparation step (1) of the hydrogel electrolyte, the amount of 0.4 g Tween 80 is replaced with 0.1 g, and the amount of 1 g 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide is replaced with 0.25 g, so as to further reduce the amount of surfactant and ionic liquid and examine their effect on the stability of the gel structure. The remaining steps are the same as in Example 1.

[0048] Example 4

[0049] The difference from Example 1 is that in the preparation step (1) of the hydrogel electrolyte, 0.12 g of phloroglucinol is replaced with 0.15 g to increase the concentration of phloroglucinol and to investigate its effect on the crosslinking density and mechanical properties of the polymer network. The remaining steps are the same as in Example 1.

[0050] Example 5

[0051] The difference from Example 2 is that in step (1), 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide is replaced with an equal mass of tributylmethylammonium bis(trifluoromethanesulfonyl)imide, and the remaining steps are the same as in Example 2.

[0052] Example 6

[0053] The difference from Example 2 is that in step (1), 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide is replaced with an equal mass of methyltributylphosphonium bis(trifluoromethanesulfonyl)imide, while the remaining steps are the same as in Example 2.

[0054] Example 7

[0055] The difference from Example 2 is that in step (1), 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide is replaced with an equal mass of 1-butyl-1-methylpyrrolidine bis(trifluoromethanesulfonyl)imide, while the remaining steps are the same as in Example 2.

[0056] Example 8

[0057] The difference from Example 2 is that in step (1), 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide is replaced with an equal mass of N-butylpyridine bis(trifluoromethanesulfonyl)imide, while the rest of the steps are the same as in Example 2.

[0058] Example 9

[0059] The difference from Example 2 is that in step (1), 0.12 g of phloroglucinol is replaced with an equal mass of hydroquinone, while the rest of the steps are the same as in Example 2.

[0060] Example 10

[0061] The difference from Example 2 is that in step (1), 0.12 g of phloroglucinol is replaced with an equal mass of resorcinol, while the rest of the steps are the same as in Example 2.

[0062] Example 11

[0063] The difference from Example 2 is that in step (1), 0.12 g of phloroglucinol is replaced with an equal mass of catechol, while the rest of the steps are the same as in Example 2.

[0064] Comparative Example 1:

[0065] The aqueous zinc ion gel electrolyte provided in this comparative example was prepared by the following method:

[0066] After adding 4 g of acrylamide and 5.7 g of zinc sulfate to 10 mL of deionized water and stirring thoroughly, 0.01 g of N,N'-methylenebisacrylamide and 0.01 g of ammonium persulfate were added to the solution and stirred at room temperature to dissolve. The resulting mixture was poured into a mold and subjected to polymerization to obtain a gel electrolyte.

[0067] Comparative Example 2:

[0068] The aqueous zinc ion gel electrolyte provided in this comparative example was prepared by the following method:

[0069] (1) At room temperature, 0.2 g of Tween 80 was added to 10 mL of deionized water and ultrasonically dispersed. Then, 0.5 g of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide was added and ultrasonically dispersed again to obtain a dispersion A containing nano-sized oil phase droplets.

[0070] (2) Add 4 g of acrylamide, 5.7 g of zinc sulfate, 0.01 g of N,N'-methylenebisacrylamide and 0.01 g of ammonium persulfate to solution A to obtain solution B. Add solution B to a mold and allow it to stand at 80 °C for polymerization until a transparent gel electrolyte is formed.

[0071] Comparative Example 3:

[0072] The aqueous zinc ion gel electrolyte provided in this comparative example was prepared by the following method:

[0073] The only difference from Example 2 is that in step (1), 0.12 g of phloroglucinol is replaced with an equal mass of phenol, and the rest of the steps are the same as in Example 2.

[0074] Performance testing

[0075] Test 1: The freeze-dried samples of the gel electrolytes prepared in Comparative Examples 1, 2, and 3, as well as Example 2, were tested using scanning electrochemical microscopy. The results are as follows: Figure 1 As shown, where Figure 1 In the examples, a represents Comparative Example 1, b represents Comparative Example 2, c represents Comparative Example 3, and d represents Example 2.

[0076] Depend on Figure 1 It can be seen that although Comparative Example 2 introduced droplet microregions formed by ionic liquid / Tween 80, the ion channels were relatively blocked, which was not conducive to ion transport; although Comparative Example 3 introduced phenol on the basis of Comparative Example 2, the overall network structure was still relatively insufficient; while Example 2 formed a more obvious porous continuous network and compartmentalized phase separation characteristics. The inventors believe that this structure originates from the effective confinement and fixation of ionic liquid microregions in the polymer continuous phase, and the interaction between the microregions and the gel network is further enhanced with the participation of phloroglucinol. This structure is beneficial to Zn 2+ On the one hand, it can migrate rapidly within the gel, and on the other hand, it can reduce the free diffusion of iodine active species and polyiodides in the electrolyte, thus providing a structural basis for improving the overall electrochemical performance of the electrolyte.

[0077] Combination Figure 1 The microstructure of the gel electrolyte shown indicates that, compared to the relatively simple and dense framework structure of Comparative Example 1 and the structure formed by introducing only ionic liquid microregions but not phloroglucinol in Comparative Example 2, Example 2 forms a more stable porous continuous network and more obvious compartmentalized phase separation characteristics. This structure is beneficial for Zn... 2+ Rapid migration within the gel, on the other hand, can confine the diffusion of iodine-active species and polyiodides, thus taking into account both ion transport and suppression of the shuttle effect.

[0078] Test 2: The gel electrolytes in Comparative Examples 1 and 2 and Example 2 were subjected to tensile stress tests, and the results are as follows: Figure 2 As shown.

[0079] Depend on Figure 2 It can be seen that, compared with Comparative Examples 1 and 2, the mechanical strength of the gel electrolyte in Example 2 is significantly improved, and its elongation at break and tensile strength are both superior to those of the comparative examples. Combined with... Figure 1 The microstructure can be considered to be that the compartmentalized phase-separated porous network formed in Example 2 and the reinforcing effect of the introduction of phloroglucinol jointly improve the stability of the gel structure, so that the resulting gel has both good flexibility and mechanical integrity.

[0080] Test 3: Tafel polarization curves were tested on the gel electrolytes in Example 2 and Comparative Examples 1 and 2 respectively. The results are as follows: Figure 3 As shown.

[0081] Depend on Figure 3As can be seen, compared with Comparative Examples 1 and 2, the corrosion current density of the gel electrolyte in Example 2 is significantly reduced, indicating that its corrosion resistance is significantly enhanced. The reason for this is that the introduction of phloroglucinol is conducive to the formation of a more stable interfacial protective layer on the zinc anode surface, while the compartmentalized phase-separated gel structure also reduces the adverse effects of the active components on the zinc surface, thereby jointly inhibiting the chemical corrosion of the zinc anode and extending the battery cycle life.

[0082] Test 4: The gel electrolytes of Examples 1-11 and Comparative Examples 1-3 were assembled into zinc-zinc symmetric batteries of the same specifications and their electrochemical performance was tested. The relevant data are summarized in Table 1.

[0083] The assembly steps of this zinc-zinc battery are as follows: zinc foil is used as the negative electrode, zinc foil is used as the positive electrode, glass fiber is used as the separator, and the prepared gel electrolyte is used to assemble a zinc-zinc symmetrical battery in a symmetrical structure.

[0084] Figure 4 The zinc-zinc symmetric cells assembled with gel electrolytes in Examples 1-4 and Comparative Examples 1 and 2 were tested at a current density of 1 mA cm⁻¹. -2 Area capacity is 1 mAh cm -2 Cyclic performance test results under the specified conditions. The results show that the gel electrolyte corresponding to Example 2 can significantly extend the cycle life of the symmetric battery.

[0085] Figure 5 The zinc-zinc symmetric batteries assembled with gel electrolytes in Example 2 and Comparative Examples 1 and 2 were also demonstrated to have an areal capacity of 1-5 mAh cm⁻¹. -2 Cyclic performance test results under various conditions. The test results show that the symmetrical cell assembled in Example 2 exhibits longer cycle life and lower overpotential under various test conditions, indicating its excellent interface stability.

[0086] Figure 6 The zinc-zinc symmetric cells assembled with gel electrolytes in Example 2 and Comparative Examples 1 and 2 of this invention were tested at a current density of 1 mA cm⁻¹. -2 Area capacity is 1 mAh cm -2 Scanning electron microscope (SEM) images of the zinc anode after 50 cycles under certain conditions, in which... Figure 6 In this context, 'a' represents comparative example 1. Figure 6 In this example, b represents comparative example 2. Figure 6 c in the example is Example 2. From Figure 6As can be seen, both Comparative Example 1 and Comparative Example 2 exhibited obvious irregular deposition and dendrite growth on their zinc anode surfaces, while the zinc anode surface of Example 2 was more uniform, dense, and smooth, with no obvious dendrite aggregation. This result corroborates the Tafel test results, indicating that the compartmentalized phase-separated gel structure formed in this invention and the interfacial synergistic regulatory effect after the introduction of phloroglucinol contribute to obtaining more uniform zinc deposition behavior.

[0087] The cycling performance results of the gel electrolyte zinc-zinc symmetric batteries corresponding to Examples 2, 5, 6, 7 and 8 show that, while keeping the [TFSI] anion constant, the ionic liquids corresponding to different cations can all form the compartmentalized phase-separated gel system described in this invention, but they differ in droplet dispersion stability, gel network structure, interface protection ability and long-term cycling performance.

[0088] The cycling performance results of the gel electrolyte zinc-zinc symmetric batteries corresponding to Examples 2, 9, 10, and 11 show that, compared with Comparative Examples 1 and 2, the gels obtained by replacing phloroglucinol with hydroquinone, resorcinol, and catechol exhibit improvements in microstructural stability, mechanical properties, zinc anode interface stability, and electrochemical cycling performance, and can replace the role of phloroglucinol under certain ratios. This is because the hydroxyl structure of polyphenolic compounds is more conducive to enhancing the interaction between the ionic liquid microdomains and the polymer network, and promoting the formation of a stable interface layer. The multi-hydroxyl structure system of this invention can achieve better overall performance, with phloroglucinol being the optimal choice.

[0089] Table 1 Test Results

[0090]

[0091] Analysis of Table 1 shows that in Comparative Example 2, although a certain microstructure can be formed by introducing only ionic liquid / Tween 80 microregions without adding phloroglucinol, the overall performance of the resulting gel is still significantly lower than that of the preferred embodiment of the present invention, resulting in relatively poor electrochemical performance of the battery. In Comparative Example 3, the electrolyte system is replaced with phenol instead of polyphenolic compounds, which severely reduces the stability of the gel microstructure, resistance to polyiodide shuttle, mechanical properties, zinc interface stability, and cycle performance, thus resulting in relatively poor electrochemical performance of the battery.

[0092] Test 5: The gel electrolytes from Example 2 and Comparative Example 1 were assembled into Zn-I2 batteries of the same specifications for electrochemical performance testing. The assembly steps of the zinc-iodine battery were as follows: zinc foil was used as the negative electrode, I2@AC as the positive electrode, and glass fiber as the separator. The gel electrolytes prepared above (Example 2 and Comparative Example 1) were used to assemble a Zn-I2 full cell.

[0093] The preparation method of the I2@AC electrode is as follows: the active material I2@AC, the conductive agent Ketjen black, and the binder CMC powder are mixed evenly in a mass ratio of 8:1:1, an appropriate amount of deionized water is added and the mixture is ground into a uniform putty-like solid, coated on a titanium mesh current collector, and dried under vacuum at 50°C to obtain the positive electrode material.

[0094] The Zn-I2 batteries assembled with the gel electrolytes in Example 2 and Comparative Example 1 were tested at 0.1~2 A g. -1 Cyclic voltammetry tests were performed at current densities to evaluate the practical application capability of the gel electrolyte, and the results are as follows: Figure 7 As shown.

[0095] Depend on Figure 7 As can be seen, compared with Comparative Example 1, Example 2 exhibits a larger peak area and a higher peak current density, and a smaller redox peak potential difference, indicating a significant improvement in reaction kinetics. The inventors believe that this is related to the rapid ion migration channels provided by the compartmentalized phase separation gel in Example 2 and the effective confinement of the diffusion of active iodine species.

[0096] Test 6: Self-discharge tests were conducted on the Zn-I2 batteries assembled with the gel electrolytes from Example 2 and Comparative Example 1 to evaluate the capacity retention of the gel electrolytes after standing for 48 hours. The results are as follows: Figure 8 As shown.

[0097] Depend on Figure 8 It can be seen that after standing for 48 hours, the capacity retention rate of Example 2 was 90.0%, while the capacity retention rate of the battery using the gel electrolyte in Comparative Example 1 was only 80.1%. The results show that the gel electrolyte in Example 2 can effectively suppress the self-discharge behavior of the battery under standing conditions. This is mainly attributed to the fact that the dense interface layer it forms effectively blocks the side reactions of the active materials and improves the storage stability of the battery.

[0098] Test 7: Cycle performance tests were conducted on the Zn-I2 all-electric batteries assembled with gel electrolytes from Example 2 and Comparative Example 1, respectively, using a LAND test system. The test voltage was 0.6-1.6V. The test results are as follows: Figure 9 , Figure 10 As shown. Figure 9 The Zn-I2 full cell assembled using the gel electrolytes from Example 2 and Comparative Example 1 of this invention was tested at 1 A g. -1 Long-cycle performance at current density; Figure 10 The Zn-I2 full cell assembled using the gel electrolyte in Example 2 of this invention is shown in 1 A g. -1 Constant current charge-discharge curves of the battery at different current densities and cycles.

[0099] Depend on Figure 9 , Figure 10 It can be seen that in 1A g -1 At the specified density, the Zn-I2 full cell assembled using the gel electrolyte in Comparative Example 1 experienced a continuous capacity decay to 78.0% after 2800 cycles; while the Zn-I2 full cell assembled using the gel electrolyte in Example 2 retained 91.0% of its capacity after 9500 cycles, demonstrating excellent long-term cycling stability.

[0100] Test 8: The Zn-I2 battery assembled with gel electrolyte in Example 2 of this invention was subjected to rate cycling performance tests on all cells using a LAND test system. The test voltage was 0.6-1.6V. The test results are as follows: Figure 11 As shown.

[0101] Depend on Figure 11 It can be seen that in the range of 0.1~5 Ag -1 Within the current density range, the Zn-I2 full cells assembled using the gel electrolyte of Example 2 maintained a high specific capacity, even at 5 A g. -1 It still exhibits good capacity retention at high rates. When the current density recovers to 0.1 A g... -1 Afterwards, the battery capacity can be quickly restored to the initial level, demonstrating excellent rate cycle stability and reversibility, which fully verifies the applicability of the gel electrolyte in high-rate application scenarios.

[0102] While specific embodiments of the present invention have been described above, those skilled in the art should understand that these are merely illustrative examples, and various changes or modifications can be made to these embodiments without departing from the principles and essence of the present invention. The scope of protection of the present invention is defined only by the appended claims.

Claims

1. A method for preparing an aqueous zinc ion gel electrolyte, characterized in that, Includes the following steps: (1) The bis(trifluoromethanesulfonyl)imine salt ionic liquid with the general formula [X][TFSI] is dispersed in a homogeneous aqueous solution formed by Tween 80, and then a polyphenolic compound is added. The dispersion containing nano-sized oil phase droplets is formed by ultrasonication. In the general formula [X][TFSI], [X] is a cation in an ionic liquid that can form with the bis(trifluoromethanesulfonyl)imide anion, and [TFSI] is the bis(trifluoromethanesulfonyl)imide anion; (2) Add acrylamide, zinc salt, N,N'-methylenebisacrylamide and ammonium persulfate to the dispersion in step (1) and stir until uniform to obtain a mixture; pour the mixture into a mold and obtain an aqueous zinc ion gel electrolyte based on bis(trifluoromethanesulfonyl)imide ionic liquid liquid phase encapsulation compartment phase separation through polymerization reaction.

2. The preparation method according to claim 1, characterized in that, The [X] is one of 1-ethyl-3-methylimidazolium cation, tributylmethylammonium cation, methyltributylphosphonium cation, 1-butyl-1-methylpyrrolidine cation, and N-butylpyridine cation.

3. The preparation method according to claim 1, characterized in that, The polyphenolic compound is at least one of hydroquinone, resorcinol, catechol, and phloroglucinol.

4. The preparation method according to claim 1, characterized in that, The zinc salt is at least one of zinc sulfate, zinc chloride, zinc perchlorate, zinc trifluoromethanesulfonate, and zinc bis(trifluoromethylsulfonyl)imide.

5. The preparation method according to claim 1, characterized in that, The mixture contains: 1-5 wt% bis(trifluoromethanesulfonyl)imine ionic liquid; 1-2 wt% Tween 80; 0.4-0.8 wt% polyphenolic compounds; 15-20 wt% acrylamide; 0.01-0.1 wt% N,N'-methylenebisacrylamide; 0.01-0.1 wt% ammonium persulfate; and 1-4 mol / L zinc salt.

6. The preparation method according to claim 1, characterized in that, In the mixture, the bis(trifluoromethanesulfonyl)imine ionic liquid is 2.5 wt%; Tween 80 is 1 wt%; polyphenolic compounds are 0.6 wt%; acrylamide is 20 wt%; zinc sulfate is 2 mol / L; N,N'-methylenebisacrylamide is 0.05 wt%; and ammonium persulfate is 0.05 wt%.

7. The preparation method according to claim 1, characterized in that, Step (1) specifically includes: first, adding Tween 80 to deionized water and dispersing it by ultrasonication, then adding bis(trifluoromethanesulfonyl)imine salt ionic liquid and continuing ultrasonic dispersion, and finally adding polyphenolic compounds and ultrasonicating them evenly.

8. The preparation method according to claim 1, characterized in that, The polymerization reaction was carried out at 60-80 °C under static conditions.

9. An aqueous zinc ion gel electrolyte, characterized in that, It is prepared by the preparation method according to any one of claims 1-8.

10. An aqueous zinc-ion battery, characterized in that, Includes the aqueous zinc ion gel electrolyte as described in claim 9.

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