Zinc-iodine battery electrode material based on MXene confined iodine monochloride and preparation method thereof

Abstract

This invention relates to the field of aqueous battery materials technology, and discloses a zinc-iodine battery electrode material based on MXene-confined iodoene and its preparation method. The electrode material is made of a mixture of few-layer MXene, few-layer iodoene, and multi-walled carbon nanotubes. In the microstructure, multi-walled carbon nanotubes are interspersed between the few-layer MXene sheets to construct a long-range continuous hybrid conductive network; the few-layer iodoene is spatially confined within the two-dimensional sheet channels of the few-layer MXene. During preparation, a flexible, self-supporting film without binder is directly formed through liquid-phase mixing, ultrasonic self-assembly, and vacuum filtration. This invention utilizes multi-walled carbon nanotubes to improve the electronic conductivity of elemental iodine, and through the size exclusion effect of the interlayer channels of few-layer MXene and the chemical coordination of its surface polar functional groups (-OH, -O, -F), it provides a physical barrier and chemical anchoring for polyiodides, suppressing the shuttle effect and improving the battery cycle stability and energy density.

Description

Technical Field

[0001] This invention relates to the field of aqueous battery materials technology, specifically to zinc-iodine battery electrode materials based on MXene-confined iodoene and their preparation methods. Background Technology

[0002] Aqueous zinc-iodine batteries possess advantages such as low cost, high safety, and high theoretical capacity, making them promising for energy storage applications. However, existing zinc-iodine batteries face technological bottlenecks. Iodine, the active material in the electrodes, is an insulator with low electronic conductivity, leading to slow reaction kinetics and increased internal polarization. During charge-discharge cycles, the conversion of solid-phase iodine to liquid-phase polyiodides causes volume expansion, disrupting the structural integrity of the electrode materials. The resulting intermediate polyiodide ions readily dissolve in the aqueous electrolyte and, driven by the concentration gradient, shuttle to the negative electrode side, reacting with metallic zinc. This polyiodide shuttle effect causes the loss of active electrode material, reducing battery capacity and cycle life.

[0003] Conventional techniques typically employ a composite approach combining elemental iodine with porous carbon materials. However, the simple physical adsorption force is weak and cannot effectively restrict the diffusion and shuttle movement of polyiodide ions in the long term. The introduction of porous carbon materials increases the weight of inactive materials, reducing the overall energy density of the battery. Current electrode fabrication processes also require the addition of polymer binders and metal current collectors, resulting in a lack of flexibility in the final electrode sheets, which cannot meet the assembly requirements of flexible energy storage devices. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides zinc-iodine battery electrode materials based on MXene-confined iodoene and their preparation method, which solves the problems of severe polyiodide shuttle effect, poor conductivity of electrode active materials, and volume expansion during charging and discharging, leading to reduced battery cycle life and capacity decay in zinc-iodine batteries.

[0005] To achieve the above objectives, the present invention provides the following technical solution: In a first aspect, the present invention provides a zinc-iodine battery electrode material based on MXene-confined iodoene, employing the following technical solution: A zinc-iodine battery electrode material based on MXene-confined iodoene is made from raw materials comprising the following parts by weight: few-layer MXene: 8-40 parts; few-layer iodoene: 40-85 parts; multi-walled carbon nanotubes: 5-20 parts; wherein the multi-walled carbon nanotubes are intercalated between the few-layer MXene sheets to form a hybrid conductive network, and the few-layer iodoene is spatially confined within the two-dimensional sheet channels of the few-layer MXene. The few-layer iodoene is confined and adsorbed by the polar functional groups on the surface of the few-layer MXene to suppress the shuttle effect of polyiodides and catalyze the conversion reaction of iodine.

[0006] Preferably, the few-layer MXene and the few-layer iodoene undergo confined adsorption and self-assembly through physicochemical interactions, and the size exclusion effect of the interlayer channels of the two-dimensional few-layer MXene is used to confine iodine and its conversion intermediates inside the nanoreactor; the few-layer iodoene and the few-layer MXene are assembled into a two-dimensional heterostructure with surface-to-surface bonding through van der Waals forces and hydrogen bonds.

[0007] Preferably, the macroscopic morphology of the electrode material is a flexible self-supporting composite film formed by mixing, filtration, and drying, and the few-layer MXene is a nanosheet obtained by peeling off a titanium aluminum carbide precursor and having polar functional groups of -OH, -O and -F on its surface.

[0008] Preferably, the few-layer iodoene is a two-dimensional iodine nanosheet obtained by liquid-phase exfoliation of commercial bulk iodine in a pure aqueous medium through ultrasonic cavitation effect.

[0009] Preferably, when the electrode material is used in an aqueous zinc-iodine battery, it is adapted to an aqueous electrolyte containing halide anions, including chloride ions. The chloride ions are used to activate and stabilize the iodine content of the electrode material during charging and discharging. 0 / I + Multi-stage conversion reactions are used to increase the overall energy density.

[0010] Secondly, the present invention provides a method for preparing a zinc-iodine battery electrode material based on MXene-confined iodoene, employing the following technical solution: A method for preparing a zinc-iodine battery electrode material based on MXene-confined iodoene includes the following steps: A few-layer MXene aqueous dispersion and a multi-walled carbon nanotube aqueous dispersion are mixed uniformly and magnetically stirred to form a mixed conductive framework precursor solution; under ice bath conditions, the mixed conductive framework precursor solution is slowly added dropwise to a few-layer iodoene pure aqueous dispersion, and after mixing, ultrasonic treatment is performed to utilize the physicochemical interaction between few-layer MXene and few-layer iodoene to induce confined adsorption and self-assembly, resulting in a mixed suspension; the mixed suspension is transferred to a microporous filter membrane for vacuum filtration, and after filtration, it is vacuum dried; after drying, the attached film is peeled off from the filter membrane to obtain the electrode material.

[0011] Preferably, before uniformly mixing the few-layer MXene aqueous dispersion and the multi-walled carbon nanotube aqueous dispersion and magnetically stirring to form a mixed conductive framework precursor solution, the titanium aluminum carbide precursor powder is pre-treated as follows to obtain the few-layer MXene aqueous dispersion: the titanium aluminum carbide precursor powder is added to an aqueous hydrochloric acid solution containing lithium fluoride, and the reaction is continuously stirred at a constant temperature of 30°C to 50°C for 36 to 60 hours; after the reaction, the precipitate is centrifuged and repeatedly washed with deionized water until neutral, the bottom precipitate is collected and dried at 4°C; the dried multilayer MXene is redispersed in deionized water, treated with an ultrasonic disruptor for 20 to 40 minutes, and then the supernatant is collected by centrifugation to obtain the few-layer MXene aqueous dispersion.

[0012] Preferably, under the ice bath conditions, before slowly adding the mixed conductive framework precursor solution to the few-layer iodine pure aqueous dispersion, the bulk iodine is pretreated as follows to obtain the few-layer iodine pure aqueous dispersion: commercial bulk iodine is dispersed in pure deionized water; the reactor containing the mixture is placed in an ice-water bath, and the pure aqueous phase is stripped using an ultrasonic pulverizer, with the ultrasonic power set to 400W to 800W, for a cumulative treatment of 3 to 5 hours; after the stripping is completed, the unstripped bulk precipitate at the bottom is removed by centrifugation, the supernatant is retained, centrifuged again, and the upper suspension is collected to obtain the few-layer iodine pure aqueous dispersion.

[0013] Preferably, when the few-layer MXene aqueous dispersion and the multi-walled carbon nanotube aqueous dispersion are mixed evenly and magnetically stirred to form a mixed conductive framework precursor solution, the magnetic stirring time at room temperature is controlled to be between 10 min and 30 min.

[0014] Preferably, the temperature of the ice bath is controlled between 0°C and 10°C, the power of the ultrasonic treatment is controlled between 50W and 100W, and the time of the ultrasonic treatment is controlled between 5min and 15min.

[0015] Preferably, the microporous filter membrane used for vacuum filtration is a polytetrafluoroethylene filter membrane with a pore size of 0.22 μm to 0.45 μm; the temperature of vacuum drying is controlled between 20°C and 40°C, and the drying time is controlled between 12 h and 24 h.

[0016] This invention provides a zinc-iodine battery electrode material based on MXene-confined iodoene and its preparation method. It has the following beneficial effects: 1. This invention employs multi-walled carbon nanotubes interspersed between few-layer MXene sheets to construct a hybrid conductive network, which supports the two-dimensional few-layer MXene sheets, prevents the sheets from stacking, and increases the interlayer volume inside the material. The multi-walled carbon nanotubes establish long-range continuous electron transport channels inside the material, improve the intrinsic insulation defects of elemental iodine, and enhance the overall electronic conductivity and structural stability of the electrode.

[0017] 2. This invention spatially confines few-layer iodoene within the two-dimensional sheet channels of few-layer MXene, utilizing the size exclusion effect of the two-dimensional interlayer channels to limit the volume expansion caused by the transformation of iodine species during the charge-discharge reaction. Simultaneously, the polar functional groups such as -OH, -O, and -F on the surface of few-layer MXene chemically coordinate with polyiodides, confining and adsorbing intermediates. Through the combination of physical spatial barriers and chemical anchoring, the dissolution and shuttle pathways of free polyiodide ions into the electrolyte are blocked, the shuttle effect is suppressed, and the cycle stability and active material utilization rate of zinc-iodine batteries are improved.

[0018] 3. This invention prepares electrode materials into flexible self-supporting composite films through a mixed filtration and vacuum drying process, eliminating the need for polymer binders and metal current collectors required for conventional electrode coating preparation, reducing the mass ratio of inactive materials in the electrode, improving the overall energy density of the battery, and the electrode composite material after film formation has macroscopic flexibility that resists bending, meeting the structural assembly requirements of flexible energy storage devices.

[0019] 4. This invention utilizes Cl in the electrolyte. - Chemical coordination activates and stabilizes the high potential of iodine (I). 0 / I + The electrocatalytic acceleration effect of MXene's polar functional groups and the regulation of halide ions complement each other in the iodine conversion reaction, successfully breaking through the kinetic and capacity bottlenecks of the traditional single-electron reaction in zinc-iodine batteries, and realizing continuous multi-stage iodine (I) conversion reaction. - ↔I 0 ↔I + The efficient and stable conversion of four electrons significantly improves the working voltage platform and overall energy density of zinc-iodine batteries. Detailed Implementation

[0020] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the preparation examples, examples, comparative examples, and test examples. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0021] It should be noted that the concentration (mg / mL) of the active substance contained in each dispersion obtained in the preparation examples of this invention can be determined accurately before use by conventional sampling, drying, and weighing methods. In the following examples, the absolute dry weight (mg) calculated by multiplying the volume (mL) of each dispersion by its corresponding concentration (mg / mL) is numerically proportional to the parts by weight. For ease of understanding, the conversion relationship of 1 mg to 1 part by weight is uniformly adopted in the embodiments of this invention.

[0022] Preparation Examples 1-3: Preparation Example 1: This preparation example provides a method for preparing few-layer MXene and few-layer iodoene dispersions, including the following steps: Preparation of few-layer MXene dispersion: 0.8 g of lithium fluoride was slowly added to 12 mL of 6 M hydrochloric acid aqueous solution and magnetically stirred for 10 min in an ice-water bath to dissolve it. 0.3 g of titanium aluminum carbide (Ti3AlC2) precursor powder was slowly added in batches under continuous stirring. The reaction system was transferred to a water bath and stirred continuously at 30 °C for 36 h. After the reaction, the suspension was centrifuged at 4000 r / min and the precipitate was repeatedly washed with deionized water until the pH of the supernatant reached neutral. The bottom layer of multilayer MXene precipitate was collected and dried at 4 °C. The dried multilayer MXene was redispersed in 100 mL of deionized water and treated with a probe-type ultrasonic disruptor for 20 min. After ultrasonic treatment, the mixture was centrifuged at 3500 r / min for 5 min and the upper layer of few-layer MXene aqueous dispersion containing abundant intrinsic surface functional groups (-OH, -O, -F, etc.) was collected.

[0023] Preparation of few-layer iodoene dispersion: Take 3.0 g of commercial bulk iodine and disperse it directly in 80 mL of pure deionized water; place the reactor containing the mixture in an ice-water bath and use a probe-type ultrasonic disruptor to perform liquid-phase separation in pure water. Set the ultrasonic power to 400 W and process for a total of 3 h. Utilize the strong cavitation effect generated by ultrasound in the aqueous medium to overcome the van der Waals forces between iodine layers; after separation, centrifuge the suspension at 3000 r / min for 5 min to remove the unseparated bulk precipitate at the bottom. Take the supernatant and centrifuge it again at 2000 r / min for 5 min. Collect the upper suspension to obtain the few-layer iodoene dispersion.

[0024] Preparation Example 2: This preparation example provides a method for preparing few-layer MXene and few-layer iodoene dispersions, including the following steps: Preparation of few-layer MXene dispersion: 1.0 g of lithium fluoride was slowly added to 16 mL of 6 M hydrochloric acid aqueous solution and magnetically stirred for 15 min in an ice-water bath to dissolve it. 0.45 g of titanium aluminum carbide (Ti3AlC2) precursor powder was slowly added in batches under continuous stirring. The reaction system was transferred to a water bath and stirred continuously at 40 °C for 48 h. After the reaction, the suspension was centrifuged at 4500 r / min. The precipitate was washed repeatedly with deionized water 6-8 times until the pH of the supernatant was neutral. The bottom layer of multilayer MXene precipitate was collected and dried at 4 °C. The dried multilayer MXene was redispersed in 150 mL of deionized water and treated with a probe-type ultrasonic disruptor for 30 min. After ultrasonic treatment, the mixture was centrifuged at 4000 r / min for 5 min and the upper few-layer MXene aqueous dispersion was collected. Its concentration was determined to be approximately 2.5 mg / mL.

[0025] Preparation of few-layer iodoene dispersion: Take 4.0 g of commercial bulk iodine and disperse it directly in 100 mL of pure deionized water; place the reactor containing the mixture in an ice-water bath and use a probe-type ultrasonic pulverizer to perform pure aqueous phase-liquid phase separation, set the ultrasonic power to 600 W, and process for a total of 4 h; after separation, centrifuge the suspension at 4000 r / min for 5 min to remove the unseparated bulk precipitate at the bottom and retain the supernatant; then centrifuge the supernatant again at 3000 r / min for 5 min to remove the bottom precipitate and collect the upper suspension to obtain a high-purity two-dimensional few-layer iodoene dispersion.

[0026] Preparation Example 3: This preparation example provides a method for preparing few-layer MXene and few-layer iodoene dispersions, including the following steps: Preparation of few-layer MXene dispersion: 1.2 g of lithium fluoride was slowly added to 20 mL of 6 M hydrochloric acid aqueous solution and magnetically stirred for 20 min in an ice-water bath to dissolve it. 0.6 g of titanium aluminum carbide (Ti3AlC2) precursor powder was slowly added in batches under continuous stirring. The reaction system was transferred to a water bath and stirred continuously at 50 °C for 60 h. After the reaction, the suspension was centrifuged at 5000 r / min, and the precipitate was repeatedly washed with deionized water until the pH of the supernatant reached neutral. The bottom layer of multilayer MXene precipitate was collected and dried at 4 °C. The dried multilayer MXene was redispersed in 200 mL of deionized water and treated with a probe-type ultrasonic disruptor for 40 min. After ultrasonic treatment, the mixture was centrifuged at 4500 r / min for 5 min, and the upper layer of few-layer MXene aqueous dispersion was collected.

[0027] Preparation of few-layer iodoene dispersion: Take 5.0 g of commercial bulk iodine and disperse it directly in 120 mL of pure deionized water; place the reactor containing the mixture in an ice-water bath and use a probe-type ultrasonic pulverizer to perform pure aqueous phase-liquid phase separation, set the ultrasonic power to 800 W, and process for a total of 5 h; after separation, centrifuge the suspension at 4500 r / min for 5 min to remove the unseparated bulk precipitate at the bottom and retain the supernatant; then centrifuge the supernatant again at 3500 r / min for 5 min to remove the bottom precipitate and collect the upper suspension to obtain the two-dimensional few-layer iodoene dispersion. Examples 1-3: Example 1:

[0028] This embodiment provides a zinc-iodine battery electrode material based on MXene-confined iodoene and its preparation method, including the following steps: Take 8.0 mL of the few-layer MXene dispersion with a concentration of 1.0 mg / mL prepared in Preparation Example 1, add 12 mL of multi-walled carbon nanotube aqueous dispersion with a concentration of 1.0 mg / mL, and stir magnetically for 10 min at room temperature to form a uniform mixed conductive framework precursor solution. Under ice bath conditions at 0°C, the above precursor solution was slowly added to the few-layer iodine dispersion prepared in Preparation Example 1 containing 80 mg of iodine. After the addition was completed, the mixture was ultrasonically treated for 10 min at a power of 50 W. The strong physicochemical interaction between the abundant surface functional groups of MXene and iodine was utilized to allow for confined adsorption and self-assembly flocculation. The mixture was poured into a vacuum filtration device equipped with a polytetrafluoroethylene microporous filter membrane with a pore size of 0.22 μm for filtration. After filtration, the film attached to the filter membrane was placed in a vacuum drying oven and dried at 20°C for 12 h. After drying, the film was peeled off from the filter membrane to obtain a flexible self-supporting composite electrode film with a mass percentage of 8% few-layer MXene, 80% iodoene, and 12% multi-walled carbon nanotubes.

[0029] The prepared composite electrode film was cut into 10 mm diameter discs using a stamping machine to serve as the positive electrode, and a 50 μm thick high-purity zinc foil was used as the negative electrode. Glass fiber filter paper was used as the separator. A mixed aqueous solution containing 1.0 M zinc sulfate and 0.1 M potassium chloride was prepared as the electrolyte. 20 μL of the electrolyte was injected into a button cell and encapsulated to obtain an aqueous zinc-iodine battery. Example 2:

[0030] This embodiment provides a zinc-iodine battery electrode material based on MXene-confined iodoene and its preparation method, including the following steps: Take 10 mL of the few-layer MXene dispersion with a concentration of 1.0 mg / mL prepared in Preparation Example 2, add 5 mL of multi-walled carbon nanotube aqueous dispersion with a concentration of 1.0 mg / mL, and stir magnetically for 20 min at room temperature to form a mixed conductive framework precursor solution. Under ice bath conditions, the above mixed suspension was slowly added to 600 mL of a few-layer iodine suspension containing about 85 mg of iodoene prepared in Preparation Example 2. After mixing, the mixture was sonicated at 70 W for 5 min to allow the MXene sheets to be fully adsorbed and confined by surface polar functional groups (such as -OH, -O, -F, etc.) and to undergo self-assembly. The obtained mixed solution was poured into a vacuum filtration device equipped with a polytetrafluoroethylene microporous filter membrane for filtration. After filtration, the film attached to the filter membrane was vacuum dried together with the filter membrane at room temperature. After drying, the film was peeled off from the filter membrane to obtain a flexible self-supporting MXene / iodoene composite electrode film with a mass percentage of 10% few-layer MXene, 85% iodoene, and 5% multi-walled carbon nanotubes.

[0031] The prepared composite electrode film was cut into 12mm diameter discs using a die-cutting machine to serve as the positive electrode. A 100μm thick high-purity zinc foil was used as the negative electrode, and glass fiber filter paper was used as the diaphragm. A solution containing 2.0M zinc sulfate and 1.0M potassium chloride (providing Cl) was prepared. - Used to activate I 0 / I + A mixed aqueous solution of the reaction was used as the electrolyte; 40 μL of the above electrolyte was injected into a button cell and then encapsulated to obtain an aqueous zinc-iodine battery. Example 3:

[0032] This embodiment provides a zinc-iodine battery electrode material based on MXene-confined iodoene and its preparation method, including the following steps: Take 8.0 mL of the few-layer MXene dispersion with a concentration of 5.0 mg / mL prepared in Preparation Example 3, add 20 mL of multi-walled carbon nanotube aqueous dispersion with a concentration of 1.0 mg / mL, and stir magnetically for 30 min at room temperature to form a uniform mixed conductive framework precursor solution. Under ice bath conditions at 10°C, the above precursor solution was slowly added dropwise to the few-layer iodine dispersion prepared in Preparation Example 3 containing 40 mg of iodine. After the addition was completed, the mixture was sonicated at 100 W for 15 min to fully induce confined self-assembly by utilizing the steric hindrance effect and surface chemical activity of the MXene sheet two-dimensional channel. The mixture was poured into a vacuum filtration device equipped with a polytetrafluoroethylene microporous filter membrane with a pore size of 0.45 μm for filtration. After filtration, the film attached to the filter membrane was placed in a vacuum drying oven and dried at 40°C for 24 h. After drying, the film was peeled off from the filter membrane to obtain a flexible self-supporting composite electrode film with a mass percentage of 40% few-layer MXene, 40% iodoene, and 20% multi-walled carbon nanotubes.

[0033] The prepared composite electrode film was cut into 16 mm diameter discs using a die-cutting machine to serve as the positive electrode. A 200 μm thick high-purity zinc foil was used as the negative electrode, and glass fiber filter paper was used as the separator. A mixed aqueous solution containing 3.0 M zinc sulfate and 2.0 M potassium chloride was prepared as the electrolyte. 60 μL of the electrolyte was injected into a button cell and encapsulated to obtain an aqueous zinc-iodine battery.

[0034] Comparative Examples 1-4: Comparative Example 1: Compared with Example 2, the difference is that no few-layer MXene dispersion was added. Instead, an equal mass (10 mg) of multi-walled carbon nanotube aqueous dispersion was used. That is, only the multi-walled carbon nanotubes and few-layer iodoene suspension were mixed, ultrasonicated, and filtered for assembly. The remaining steps and test conditions were the same.

[0035] Comparative Example 2: Compared with Example 2, the difference is that the few-layer iodoene dispersion prepared by pure aqueous phase liquid-phase exfoliation was not used. Instead, an equal mass of commercial bulk iodine powder that had not been ultrasonically exfoliated was directly added to the mixture for ultrasonic assembly. All other steps and test conditions were the same.

[0036] Comparative Example 3: Compared with Example 2, the difference is that multi-walled carbon nanotube aqueous dispersion was not added to the mixed conductive framework precursor solution. Instead, 15 mL (i.e., 5 mg of the corresponding mass) of few-layer MXene dispersion was used directly to keep the total mass of solid content unchanged. The remaining steps and test conditions were the same.

[0037] Comparative Example 4: Compared with Example 2, the difference is that potassium chloride (KCl) is not added when preparing the aqueous electrolyte. Instead, a single aqueous solution of zinc sulfate (ZnSO4) with a concentration of 2.0M is used as the electrolyte for the battery. All other assembly and testing conditions are the same.

[0038] Test Example 1-2: Test Example 1: This test case provides electrochemical rate performance and multi-stage conversion kinetics tests for aqueous zinc-iodine batteries, primarily used to verify the highly efficient catalytic effect of the MXene host on iodine species and the concentration of Cl in the electrolyte. -to I 0 / I + The activation effect of high-potential reactions.

[0039] The button-type aqueous zinc-iodine batteries assembled in Examples 1-3 and Comparative Examples 1-4 were used as test subjects. Constant current charge-discharge tests were performed on each battery using a battery testing system at room temperature (25°C). To fully evaluate the kinetic characteristics and high-rate tolerance of the batteries at different reaction stages, a test voltage window was set, and tests were conducted sequentially at 0.5Ag... -1 Up to 10Ag -1 The charge-discharge curves and specific capacity were recorded under different current densities.

[0040] Test results show that, due to the use of a two-dimensional pure aqueous phase exfoliated few-layer iodoene and few-layer MXene tightly confined structure, and the combination of Cl-containing... - The electrolyte exhibits excellent reaction kinetics and multi-stage transformation characteristics. Specifically, it demonstrates the following: Very low charge-discharge polarization: at 0.5Ag -1 At low current densities, the charge-discharge curves of Example 2 clearly demonstrate continuous multi-stage (I) - ↔I 0 ↔I + The voltage plateau of the transition. Its high potential range (I) 0 / I + The polarization voltage of ) is only 0.07V, and the low potential range (I) - / I 0 The polarization voltage of the control sample was as low as 0.04V. In contrast, the polarization voltage of Comparative Example 1 (without MXene) and Comparative Example 4 (without halide ion modulation) increased, and Comparative Example 4 completely failed to exhibit stable Ig. 0 / I + A high-voltage platform. This fully demonstrates the powerful electrocatalytic accelerating effect of the polar functional groups (-OH, -F, -O) on the iodine conversion reaction of MXene, and the effect of Cl... - The stabilizing effect of chemical coordination on highly active steps.

[0041] Extremely high rate performance: When the charge / discharge current density increases dramatically by 20 times to 10Ag -1 Even under high-rate operating conditions, Example 2 can still release up to 206 mAh g. -1 The high reversible specific capacity of the MXene nanoreactor is evident. In contrast, Comparative Example 2, using unexfoliated bulk iodine, suffers from severe capacity decay at high rates due to the large volume of the active material and long ion / electron transport paths, making normal charge-discharge almost impossible. This demonstrates that the MXene-confined two-dimensional iodoene nanoreactor constructed in this invention optimizes the charge transport network within the electrode, reduces interfacial resistance, and overcomes the kinetic bottleneck of traditional single-electron reactions.

[0042] Test Example 2: This test case provides a comprehensive performance evaluation of aqueous zinc-iodine batteries, including long cycle life, suppression of the shuttle effect (self-discharge test), and overall energy and power density. It is primarily used to verify the radical effect of the MXene nanoreactor on the polyiodide shuttle effect and the multi-stage reaction (I... - ↔I 0 ↔I + This improves the overall energy output of the battery.

[0043] Continue to use the button batteries assembled in Examples 1-3 and Comparative Examples 1-4, and conduct long-cycle constant current charge-discharge tests and static self-discharge tests at room temperature using a multi-channel battery testing system. Combine the discharge specific capacity and working voltage platform to calculate their energy density (based on the total mass of electrode active materials) and power density.

[0044] Test results show that Example 2 exhibits high stability and breakthrough energy output, as detailed below: Ultra-long cycle life: at 5Ag -1 At high current densities, the battery in Example 2 maintained a capacity retention of up to 97% after 6000 continuous charge-discharge cycles, and the discharge voltage plateau showed no significant signs of decay; further increasing the current density to 10 Ag... -1 After 10,000 cycles at high rates, the battery performance showed no significant degradation. In contrast, Comparative Example 1 (using only carbon nanotube physical adsorption) without MXene showed a precipitous capacity decay in the early stages of cycling, proving that purely physical pores cannot effectively anchor intermediate products; while Comparative Example 3 without carbon nanotubes also failed to maintain long-term cycling due to the breakdown of the conductive network caused by the stacking of two-dimensional sheets. This strongly confirms that the MXene host completely solves the problem of electrode active material loss caused by polyiodide dissolution through the dual effects of strong physical spatial confinement and surface chemical adsorption.

[0045] Suppressing the shuttle effect and exhibiting a very low self-discharge rate: After the fully charged battery was left to stand for several days, a discharge test was conducted. Example 2 demonstrated a very low self-discharge rate and excellent shelf stability. This is attributed to the size exclusion effect of the two-dimensional MXene interlayer channels and its abundant surface polar groups, which firmly imprison iodine and its conversion intermediates inside the nanoreactor, cutting off the shuttle path for polyiodides to migrate to the zinc anode, thus avoiding severe self-discharge and anode corrosion.

[0046] High energy and power density: thanks to the structural protection of MXene and the Cl in the electrolyte - Through the synergistic effect of chemical coordination, Example 2 achieved for the first time an efficient and stable multi-stage (I-) coagulation of iodine in the same electrode.- ↔I 0 ↔I + Four-electron conversion. Calculations show that the battery's maximum energy density can reach 640 Wh / kg. -1 The highest power density is up to 12600Wkg. -1 In contrast, without added Cl - Comparative Example 4 can only occur in the traditional I - The I+ single-electron reaction not only has a low operating voltage plateau, but also a limited theoretical capacity (only about 211 mAh g). -1 Its energy density is far lower than that of Example 2. This indicates that the internal and external synergistic strategy of the present invention has successfully broken through the energy density bottleneck of single-electron reaction in traditional aqueous zinc-iodine batteries, and is superior to most existing reported aqueous intercalated batteries.

[0047] The results of Test Example 1 and Test Example 2 show that the present invention prepares two-dimensional few-layer iodoenes through pure aqueous phase liquid-phase exfoliation and precisely confines them within few-layer MXene channels that also have a two-dimensional structure, in conjunction with Cl-containing... - By controlling the aqueous electrolyte, a high-performance composite electrode material with both confinement and catalytic effects was successfully constructed. This approach achieves a balance between multi-stage conversion and high stability without sacrificing long cycle life, overcoming the three inherent defects of traditional zinc-iodine batteries: polyiodide shuttle, slow kinetics, and limited energy density.

Claims

1. A zinc-iodine battery electrode material based on MXene-confined iodoene, characterized in that, Made from raw materials comprising the following parts by weight: Few layers of MXene: 8-40 parts; Lesser-layered iodoene: 40–85 parts; Multi-walled carbon nanotubes: 5–20 parts; The multi-walled carbon nanotubes are interspersed between the few-layer MXene sheets to form a hybrid conductive network. The few-layer iodoene is spatially confined within the two-dimensional sheet channels of the few-layer MXene. The few-layer iodoene is confined and adsorbed by the polar functional groups on the surface of the few-layer MXene to suppress the shuttle effect of polyiodides and catalyze the conversion reaction of iodine.

2. The zinc-iodine battery electrode material based on MXene-confined iodoene according to claim 1, characterized in that, The few-layer MXene and few-layer iodoene undergo confined adsorption and self-assembly through physicochemical interactions, and the size exclusion effect of the two-dimensional few-layer MXene interlayer channels is used to confine iodine and its conversion intermediates inside the nanoreactor. The few-layer iodoene and the few-layer MXene interact through van der Waals forces and hydrogen bonds to assemble into a two-dimensional heterostructure with face-to-face bonding.

3. The zinc-iodine battery electrode material based on MXene-confined iodoene according to claim 1, characterized in that, The macroscopic morphology of the electrode material is a flexible self-supporting composite film formed by mixing, filtration, and drying. The few-layer MXene is a nanosheet obtained by peeling off a titanium aluminum carbide precursor and has polar functional groups of -OH, -O and -F on its surface.

4. The zinc-iodine battery electrode material based on MXene-confined iodoene according to claim 1, characterized in that, The few-layer iodoene is a two-dimensional iodine nanosheet obtained by liquid-phase exfoliation of commercial bulk iodine in a pure aqueous medium through ultrasonic cavitation effect.

5. The method for preparing zinc-iodine battery electrode material based on MXene confined iodoene according to any one of claims 1-4, characterized in that, Includes the following steps: A few-layer MXene aqueous dispersion and a multi-walled carbon nanotube aqueous dispersion were mixed evenly and magnetically stirred to form a mixed conductive framework precursor solution. Under ice bath conditions, the mixed conductive framework precursor solution was slowly added dropwise to the few-layer iodine pure water dispersion. After mixing, the mixture was subjected to ultrasonic treatment. The physicochemical interaction between the few-layer MXene and the few-layer iodine caused them to undergo confined adsorption and self-assembly, resulting in a mixed suspension. The mixed suspension is transferred to a microporous filter membrane for vacuum filtration. After filtration, it is vacuum dried. After drying, the attached film is peeled off from the filter membrane to obtain the electrode material.

6. The method for preparing zinc-iodine battery electrode material based on MXene-confined iodoene according to claim 5, characterized in that, Before mixing the few-layer MXene aqueous dispersion and the multi-walled carbon nanotube aqueous dispersion evenly and magnetically stirring to form a mixed conductive framework precursor solution, the titanium aluminum carbide precursor powder is pre-treated as follows to obtain the few-layer MXene aqueous dispersion: Titanium aluminum carbide precursor powder was added to an aqueous hydrochloric acid solution containing lithium fluoride and stirred continuously at a constant temperature of 30℃~50℃ for 36h~60h. After the reaction was completed, the precipitate was centrifuged and repeatedly washed with deionized water until neutral. The bottom precipitate was collected and dried at 4°C. The dried multilayer MXene was redispersed in deionized water and treated with an ultrasonic disruptor for 20 to 40 minutes. The supernatant was then collected by centrifugation to obtain the multilayer MXene aqueous dispersion.

7. The method for preparing zinc-iodine battery electrode material based on MXene confined iodoene according to claim 5, characterized in that, Before slowly adding the mixed conductive framework precursor solution to the few-layer iodine pure aqueous dispersion under the ice bath conditions, the bulk iodine is pretreated as follows to obtain the few-layer iodine pure aqueous dispersion: Commercial block iodine was dispersed in pure deionized water; The reactor containing the mixture was placed in an ice-water bath, and the pure aqueous phase was separated from the liquid phase using an ultrasonic pulverizer. The ultrasonic power was set to 400W to 800W, and the cumulative treatment time was 3 to 5 hours. After the stripping is completed, the unstripped precipitate at the bottom is removed by centrifugation. The supernatant is retained and centrifuged again to collect the upper suspension, thus obtaining the few-layer iodoene pure water dispersion.

8. The method for preparing zinc-iodine battery electrode material based on MXene confined iodoene according to claim 5, characterized in that, When the few-layer MXene aqueous dispersion and the multi-walled carbon nanotube aqueous dispersion are mixed evenly and magnetically stirred to form a mixed conductive framework precursor solution, the magnetic stirring time is controlled at 10 min to 30 min at room temperature.

9. The method for preparing zinc-iodine battery electrode material based on MXene confined iodoene according to claim 5, characterized in that, The temperature of the ice bath is controlled between 0°C and 10°C, the power of the ultrasonic treatment is controlled between 50W and 100W, and the time of the ultrasonic treatment is controlled between 5min and 15min.

10. The method for preparing zinc-iodine battery electrode material based on MXene confined iodoene according to claim 5, characterized in that, The microporous filter membrane used for vacuum filtration is a polytetrafluoroethylene filter membrane with a pore size of 0.22 μm to 0.45 μm; The temperature of the vacuum drying is controlled between 20℃ and 40℃, and the drying time is controlled between 12h and 24h.