A novel ionic polymer solid-state electrolyte, a preparation method thereof and application thereof in zinc-iodine batteries

Abstract

This invention relates to a novel ionic polymer solid electrolyte, its preparation method, and its application in zinc-iodine batteries, belonging to the field of new energy materials and electrochemical technology. The electrolyte is prepared by casting an ionic polymer (composed of an active halogen monomer I and a nitrogen-containing compound II with strong nucleophilicity), a polymer matrix, a zinc salt, and an organic solvent. The halogen anion acts as a reaction medium, exciting and stabilizing I. ‑ / I 0 / I + The four-electron reaction enhances the specific capacity of the cathode and the energy density of the battery; the polymer framework constructs efficient ion-selective channels that suppress polyiodide shuttle and enhance reaction reversibility; active nitrogen ions promote zinc salt dissociation, accelerate zinc ion transport kinetics, and achieve uniform zinc ion deposition. This invention achieves an integrated electrolyte design that regulates the cathode reaction path, suppresses the shuttle effect, and synergistically enhances the anode interface, providing a solution for constructing high-energy-density, long-life, and high-safety zinc-iodine batteries.

Description

Technical Field

[0001] This invention belongs to the field of new energy materials and electrochemical technology, specifically relating to a novel ionic polymer solid electrolyte, its preparation method, and its application in zinc-iodine batteries. Background Technology

[0002] With the accelerated global energy transition to renewable energy, the development of electrochemical energy storage systems with high safety, low cost, and high energy density has become an urgent need. Aqueous zinc-ion batteries, due to their high safety, low cost, and environmental friendliness, have emerged as a promising electrochemical energy storage technology. Currently, the low theoretical specific capacity and complex phase transition processes of manganese-based and vanadium-based cathode systems severely limit further improvements in the energy density of aqueous zinc-ion batteries. Therefore, rechargeable zinc-iodine batteries have attracted widespread attention due to the abundant reserves of I2 cathode material (55 μg / L in seawater) and its high theoretical specific capacity (422 mAh / g, based on a four-electron reaction), marking a transition in cathode materials for aqueous zinc-ion batteries from transition metal oxides to halogen conversion materials.

[0003] However, the application of high-energy-density zinc-iodine batteries in traditional liquid electrolyte systems still faces some challenges. For example, on the zinc anode side, zinc metal is thermodynamically unstable in aqueous electrolytes, making it prone to side reactions such as hydrogen evolution and corrosion. Furthermore, uneven deposition of zinc ions can easily form zinc dendrites, which may penetrate the separator and cause short circuits, severely affecting the battery's cycle life and safety. Simultaneously, on the I2 cathode side, the poorly conductive I2 can form soluble polyiodides (I2 + I...). - → I3 - I2+ I3 - → I5 - (etc.), while the polyiodides dissolved in the electrolyte diffuse to the negative electrode and undergo irreversible reactions with zinc metal (e.g., Zn + I3). - → Zn 2+ + 3I - This leads to continuous loss of positive electrode active material, decreased coulombic efficiency, and severe self-discharge. In particular, based on I... - / I 0 / I + The four-electron conversion reaction forms a high-valence I + In aqueous electrolytes, the thermodynamic stability is poor, and hydrolysis reactions are very likely to occur, leading to the failure of active materials, reduced coulombic efficiency and voltage decay, and also compromising the stability of the electrolyte.

[0004] Currently, in order to enhance I-based - / I 0 / I +The reversibility of the four-electron conversion reaction is typically achieved using an ultra-high concentration halide ion electrolyte strategy (≥5 M ZnCl2), through a high concentration of Cl... - with I + The formation of interhalogen compounds or polyhalogen complexes stabilizes the I₂ generated in the four-electron conversion reaction. + Simultaneously, high-concentration electrolytes can significantly reduce the activity of free water, thereby inhibiting I... + Hydrolysis. However, high concentrations of free halide ions (such as Cl-) - , Br - The electrolyte exhibits strong corrosiveness to the zinc anode, accelerating its failure and accompanied by side reactions such as hydrogen evolution. Secondly, the high-concentration electrolyte fails to solve the dissolution and shuttle problem of polyiodides. Furthermore, the ultra-high concentration leads to a sharp increase in electrolyte viscosity and a significant decrease in ionic conductivity, resulting in a severe decline in electrochemical reaction kinetics and thus affecting the battery's rate performance.

[0005] To address the aforementioned issues, existing research often employs solid-state electrolytes to replace traditional liquid electrolyte systems. These solid-state electrolytes effectively suppress the dissolution and migration of polyiodides through physical barriers, fundamentally resolving the shuttle effect of polyiodides. This not only increases the utilization rate of the active material in the I2 cathode but also inhibits corrosion of the zinc metal anode, thereby improving the reversible capacity and safety of the battery. However, conventional solid-state electrolytes are limited in their application in zinc-iodine batteries due to their low ionic conductivity, high crystallinity, and poor compatibility with electrode interfaces. In particular, conventional solid-state electrolytes (such as pure polymer matrices) often struggle to balance high ionic conductivity with selective ion transport capabilities and lack the ability to actively regulate the redox reaction pathway of iodine, failing to overcome the capacity bottleneck of the two-electron reaction and the I2+ ion transport mechanism. + The stability of ions is a challenge. Furthermore, poor solid-solid contact between the solid electrolyte and the zinc metal anode easily leads to increased interfacial impedance and uneven zinc ion flux distribution, which in turn triggers zinc dendrite growth and interfacial failure, further exacerbating anode corrosion and inducing battery safety issues. Ionic polymers, through the design of the matrix structure and functional groups, simultaneously introduce fixed-charge groups and mobile counterions (i.e., possessing both positive and negative ion centers) into the structure, enabling precise control of ion transport, enhanced interfacial compatibility, and improved performance based on I-... - / I 0 / I + The active excitation and stabilization effect of the four-electron conversion reaction.

[0006] Therefore, developing a multifunctional ionic polymer electrolyte that can excite and stabilize the four-electron conversion reaction of I2 cathode, efficiently suppress polyiodide shuttle, and promote uniform transport and deposition of zinc ions is a key way to break through the technological bottleneck of high energy density and long life zinc-iodine batteries, and has important innovative significance and application value. Summary of the Invention

[0007] This invention addresses the technical problems of conventional polymer solid electrolytes in the prior art, which struggle to simultaneously achieve high ionic conductivity and selective ion transport capabilities, and lack the ability to actively regulate the redox reaction pathway of iodine. It provides a novel ionic polymer solid electrolyte, its preparation method, and its application in zinc-iodine batteries. This invention achieves a multifunctional electrolyte integrated design that integrates positive electrode reaction pathway regulation, effective suppression of the multi-iodide shuttle effect, and synergistic enhancement of zinc metal anode interface kinetics, providing a solution for constructing high-energy-density, long-cycle-life, and highly safe zinc-iodine batteries.

[0008] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows:

[0009] A novel ionic polymer solid electrolyte is obtained by solution casting from a novel ionic polymer, a polymer matrix, an organic solvent, and a zinc salt.

[0010] The novel ionic polymer is formed by polymerizing a monomer I containing an active halogen and a nitrogen-containing compound II with strong nucleophilicity. The monomer I containing an active halogen and the nitrogen-containing compound II with strong nucleophilicity react according to the molar ratio of nitrogen cation to halide anion.

[0011] The monomer I containing an active halogen is one or more of the following: 1,4-dibromomethylbenzene, 1,3-dibromomethylbenzene, 1,3,5-tribromomethylbenzene, 1,2,4,6-tetrabromomethylbenzene, 1,4-dichloromethylbenzene, 1,3-dichloromethylbenzene, 1,3,5-trichloromethylbenzene, 1,2,4,6-tetrachloromethylbenzene, 1,3,5-tris[4-(bromomethyl)phenyl]benzene, 2,4,6-tris(4-(bromomethyl)phenyl)-1,3,5-triazine, 1,4-bis(bromomethyl)naphthalene, 2,6-bis(bromomethyl)naphthalene, 2,7-bis(bromomethyl)naphthalene, and 4,4'-bis(bromomethyl)biphenyl.

[0012] The strongly nucleophilic nitrogen-containing compound II is one or more of the following: 1,4-bis(1H-imidazol-1-yl)benzene, 1,3-bis(1H-imidazol-1-yl)benzene, 1,3,5-tris(1H-imidazol-1-yl)benzene, 1,4-bis(1H-imidazol-1-yl)pyridazine, 1,3-bis(1H-imidazol-1-yl)pyridazine, 1,3,5-tris(1H-imidazol-1-yl)pyridazine, 2,4,6-tris(1H-imidazol-1-yl)-1,3,5-triazine, and 2,4,6-tris[4-(1H-imidazol-1-yl)-phenyl]-1,3,5-triazine.

[0013] The novel ionic polymer accounts for 3% to 20% of the mass percentage of the polymer solid electrolyte.

[0014] In the above technical solution, preferably, the monomer I containing an active halogen and the nitrogen-containing compound II with strong nucleophilicity are polymerized in a reaction solvent, which is one or more of N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), dichloromethane (DCM), toluene (Tol), and acetonitrile (ACN), and its mass is 8 to 15 times the total weight of the monomer I containing an active halogen and the nitrogen-containing compound II with strong nucleophilicity.

[0015] In the above technical solution, preferably, the zinc salt is one or more of zinc sulfate (ZnSO4), zinc bis(TFSI)2, zinc trifluoromethanesulfonate (Zn(OTf)2), zinc chloride (ZnCl2), and zinc perchlorate (Zn(ClO4)2), and the mass percentage of the zinc salt in the polymer solid electrolyte is 10% to 50%.

[0016] In the above technical solution, preferably, the polymer matrix is ​​one or more of polyethylene oxide (PEO), polyvinylidene fluoride (PVDF), polyacrylamide (PAM), polyacrylonitrile (PAN), and polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP).

[0017] In the above technical solution, preferably, the organic solvent is one or more of N,N-dimethylformamide (DMF), acetonitrile (ACN), N,N-dimethylacetamide (DMAc), dimethyl sulfoxide (DMSO), and ionic liquid.

[0018] A method for preparing a novel ionic polymer solid electrolyte includes the following steps:

[0019] Step 1: Polymerize monomer I containing active halogens and nitrogen-containing compound II with strong nucleophilicity in a reaction solvent to form a novel ionic polymer;

[0020] Step 2: Place the novel ionic polymer, polymer matrix and zinc salt from Step 1 into an organic solvent and stir thoroughly to disperse them evenly, so as to obtain a uniform and stable composite electrolyte slurry, which is the film-forming solution.

[0021] Step 3: Pour the film-forming solution from Step 2 into a mold, and after drying and demolding, obtain a novel ionic polymer solid electrolyte.

[0022] In the above technical solution, preferably, the reaction conditions for polymerization in the reaction solvent in step 1 are: stirring at 100°C for 24 h under a nitrogen atmosphere, washing three times with DMF and acetonitrile in sequence after the reaction is completed, and drying at 60°C for 24 h; the stirring time in step 2 is 12 h; and the novel ionic polymer solid electrolyte obtained in step 3 has a film thickness of 140 μm to 300 μm.

[0023] In the above technical solution, it is preferred that the drying conditions in step 3 are drying at 60°C for 8 hours.

[0024] The application of a novel ionic polymer solid electrolyte of the present invention in the preparation of a zinc-iodine battery with a four-electron conversion reaction.

[0025] In the above technical solution, preferably, the zinc-iodine battery with four-electron conversion reaction includes a novel ionic polymer solid electrolyte, and further includes a zinc metal negative electrode and an I2 positive electrode supported on activated carbon.

[0026] The beneficial effects of this invention are:

[0027] The novel ionic polymer solid electrolyte of the present invention has the following advantages:

[0028] 1. Activation and stabilization of four-electron reaction pathways: In the novel ionic polymers of this invention, halide anions (e.g., Br₂) - As a highly efficient reaction medium, its introduction can effectively excite the iodine electrode based on I. - / I 0 / I + The four-electron redox reaction significantly improves the battery's energy density; simultaneously, halide anions can react with high-valence I... + Interacting with each other, effectively inhibiting I + Hydrolysis ensures the high reversibility of the four-electron conversion reaction;

[0029] 2. Suppression of polyiodide shuttle effect: The novel ionic polymer of this invention constructs a highly efficient ion-selective transport channel with ion selectivity, which can efficiently conduct zinc ions and effectively suppress polyiodides (I3) through size effect and electrostatic interaction. - I5 - The diffusion of polyiodides (etc.) fundamentally inhibits the shuttle effect of polyiodides, thereby improving the reversibility of the reaction and the cycle stability of the battery.

[0030] 3. Regulation of zinc ion transport and deposition kinetics: In the novel ionic polymer of this invention, the active nitrogen cations can react with zinc salt anions (SO42-). 2- CF3SO3 -(etc.) to generate dynamic coordination, thereby promoting zinc salt dissociation, accelerating the transport kinetics of zinc ions in the bulk phase, and improving the bulk phase ionic conductivity; at the same time, this interaction can regulate the migration energy barrier of zinc ions at the electrode / electrolyte interface, promote the uniform deposition of zinc metal, effectively suppress dendrite growth, thereby improving the cycle life and rate characteristics of the battery.

[0031] This invention presents a novel ionic polymer solid electrolyte that overcomes the technical limitations of traditional liquid and conventional solid electrolytes. Through structural and functional ion design, it simultaneously addresses the capacity bottleneck, shuttle effect, and Ig in zinc-iodine batteries. + Problems such as stability and zinc kinetic sluggishness provide solutions for building next-generation high-energy-density, long-life, and highly safe zinc-iodine batteries. Attached Figure Description

[0032] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein:

[0033] Figure 1 The Fourier transform infrared spectrum of the novel ionic polymer prepared in Example 1 of this invention.

[0034] Figure 2 The novel ionic polymer prepared in Example 1 of this invention 13 C solid-state nuclear magnetic resonance spectrum.

[0035] Figure 3 The diagram shows the ionic conductivity of the ionic polymer solid electrolytes prepared in Example 1 and Comparative Examples 1 and 2 of this invention.

[0036] Figure 4 The graph shows the cycle performance of a Zn‖Zn symmetric battery assembled with an ionic polymer solid electrolyte prepared in Example 1 of this invention.

[0037] Figure 5 The cyclic voltammograms are of Zn‖I2 full cells assembled from the ionic polymer solid electrolytes prepared in Example 1 of the present invention and Comparative Examples 1 and 2.

[0038] Figure 6 The charge-discharge curves are shown for Zn||I2 full cells assembled from ionic polymer solid electrolytes prepared in Example 1 and Comparative Examples 1 and 2 of this invention.

[0039] Figure 7 The graph shows the long-cycle performance of a Zn‖I2 full cell assembled from the ionic polymer solid electrolyte prepared in Example 1 of this invention. Detailed Implementation

[0040] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to examples.

[0041] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0042] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0043] Unless otherwise specified, all raw materials used in this invention are commercially available in the field.

[0044] The novel ionic polymer structure characterization and electrolyte performance testing method in this invention refers to:

[0045] 13 C Solid-state nuclear magnetic resonance spectroscopy: The chemical shift of carbon in the material was measured using a Bruker Avance III 400 MHz solid-state nuclear magnetic resonance spectrometer at a magic angle rotation rate of 5 kHz, thereby determining the polymer structure.

[0046] Fourier Transform Infrared Spectroscopy: The structures of monomers and polymers were determined using a Nicolet iS50 Fourier Transform Infrared Spectrometer, with a test range of 4000-400 cm⁻¹. -1 .

[0047] Ion conductivity testing: Electrochemical impedance spectroscopy (EIS) was performed using a blocked battery on a CHI660E electrochemical workstation. Both the positive and negative electrodes of the battery were made of stainless steel. First, the volume impedance of the polymer electrolyte was obtained via EIS. (Ω). The amplitude is 5mV, and the test frequency is 1×10⁻⁶. 6 Hz-0.01 Hz. The zinc ion conductivity can be calculated using the following formula:

[0048]

[0049] Where σ (S / cm) is the ionic conductivity of the polymer solid electrolyte. (cm) represents the solid thickness of the polymer electrolyte. (cm) 2 ) represents the surface area of ​​the polymer solid electrolyte.

[0050] Zn‖Zn Symmetrical Battery Assembly: A symmetric battery is assembled using zinc sheets as electrodes and a novel ionic polymer solid electrolyte prepared in the examples.

[0051] Zn||I2 Full Cell Assembly: A full cell was assembled using zinc sheet as the negative electrode, AC@I2 as the positive electrode, and the ionic polymer solid electrolyte prepared in the examples and comparative examples. The preparation process of AC@I2 is as follows: The positive electrode was prepared by solution adsorption. 100 mg of I2 and 100 mg of activated carbon (AC) were mixed, and then 200 mL of deionized water was added. The mixture was stirred until the solution was clear. The mixture was filtered and dried to remove residual water, yielding the positive electrode material AC@I2. AC@I2, acetylene black, and polyvinylidene fluoride binder were mixed uniformly at a mass ratio of 70:20:10, and an appropriate amount of N-methylpyrrolidone was added. The mixture was stirred for 5 minutes using a high-speed degassing homogenizer to form a uniform slurry. The slurry was then coated onto carbon cloth and placed at 45°C. o The sample was dried in a vacuum drying oven at temperature C for 12 hours to remove the solvent. The active substance loading was approximately 2.0 mg / cm³. 2 All electrochemical performance test data were standardized based on the effective loading mass of iodine to ensure consistency in performance comparisons across different samples.

[0052] Cyclic voltammetry curve testing: Cyclic voltammetry curve testing was performed using a CHI660E electrochemical workstation with a test potential window of 0.4-1.8 V and a frequency range of 0.01 Hz-100 kHz.

[0053] Charge / discharge curve testing: Room temperature charge / discharge curve testing was conducted using a Newway battery tester. The Zn||I2 full cell was charged at room temperature (25°C). o Charge-discharge curves were tested at a current density of 0.2 A / g under temperature C. The charge-discharge specific capacity was recorded after two cycles. For the capacity calculation of solid-state full cells, the capacity of Zn‖I2 cells is calculated based on the mass of I2.

[0054] Room temperature long-cycle performance testing: Charge and discharge performance tests were conducted using a Newway battery tester. First, the Zn‖I2 full cell was charged and discharged at room temperature (25°C). o Long-cycle performance was tested at a current density of 4 A / g under C conditions. The charge-discharge specific capacity was recorded for different cycles. The capacity retention rate (%) of the battery after the Nth cycle was calculated as (Nth discharge specific capacity / Second discharge specific capacity) × 100%. For the capacity calculation of solid-state full cells, the capacity of Zn‖I2 cells was calculated based on the mass of I2.

[0055] Example 1

[0056] This embodiment provides a novel method for preparing an ionic polymer solid electrolyte, specifically as follows:

[0057] 1) Preparation of the novel ionic polymer: 0.356 g of 1,3,5-tribromomethylbenzene and 0.315 g of 1,4-bis(1H-imidazol-1-yl)benzene were weighed and dispersed in 20 mL of N,N-dimethylformamide (DMF), and stirred at 100 °C for 24 h under a nitrogen atmosphere. After the reaction was complete, the mixture was cooled to room temperature, the precipitate was collected by filtration, and washed three times successively with DMF and acetonitrile. The product was dried in a vacuum oven at 60 °C for 24 h to obtain the novel ionic polymer (BIB-TBMB).

[0058] 2) Preparation of the film-forming solution: Disperse 0.1 g of BIB-TBMB in 5 g of DMF by mass fraction, and stir magnetically for 12 h until the solution is uniformly dispersed. Dissolve 1 g of polyvinylidene fluoride (PVDF) and 0.7 g of zinc trifluoromethanesulfonate (Zn(OTf)2) in 10 g of DMF, and stir magnetically for 12 h until completely dissolved. Then, mix the two solutions and continue stirring for 12 h to ensure uniform dispersion of all components, forming a homogeneous viscous solution, which is the film-forming solution.

[0059] 3) Preparation of novel ionic polymer solid electrolyte: The film-forming solution was cast into a polytetrafluoroethylene (PTFE) mold, and the PTFE mold was transferred to a vacuum drying oven at 60℃ for 8 h. After demolding, a novel ionic polymer solid electrolyte with a thickness of 200 μm was obtained, denoted as BIB-TBMB / PVDF. The novel ionic polymer accounted for 5.6% of the mass percentage of the polymer solid electrolyte, and the zinc salt accounted for 39% of the mass percentage of the polymer solid electrolyte.

[0060] Comparative Example 1

[0061] The difference between this comparative example and Example 1 is that a polymer without bromide anions was prepared. Specifically, 0.1 g of BIB-TBMB and excess ammonium hexafluorophosphate were dispersed in 15 mL of deionized water and stirred at 100°C for 24 h under a nitrogen atmosphere. After the reaction was completed, the mixture was cooled to room temperature, the precipitate was collected by filtration, and washed three times with deionized water. The product was then dried in a vacuum oven at 60°C for 24 h to obtain the novel ionic polymer.

[0062] The remaining steps and processes were all performed in accordance with Example 1 to obtain the novel ionic polymer solid electrolyte of this comparative example.

[0063] Comparative Example 2

[0064] The difference between this comparative example and Example 1 is that the 1,4-bis(1H-imidazol-1-yl)benzene in step 1) is replaced with sodium terephthalate, while the remaining steps are the same as in Example 1, to obtain the novel ionic polymer solid electrolyte of this comparative example.

[0065] The structure and composition of the novel ionic polymer prepared in Example 1 were characterized and analyzed, and the results are as follows: Figures 1-2 As shown.

[0066] Figure 1 The Fourier transform infrared spectra of the novel ionic polymer prepared in Example 1 and its raw material 1,3,5-tribromomethylbenzene are shown. The results indicate that in Example 1, the 1067 cm⁻¹... -1 The absorption peak at 701 cm⁻¹ is attributed to the CN vibration peak, while the absorption peak at 701 cm⁻¹ is also attributed to the CN vibration peak. -1 The disappearance of the nearby C-Br bond vibration peak indicates the successful preparation of the novel ionic polymer in Example 1.

[0067] Figure 2 The novel ionic polymer prepared in Example 1 of this invention 13 The results of the C solid-state nuclear magnetic resonance spectrum show that: 13 The characteristic peaks in the C-spectrum all correspond to the different carbon atom assignments in the novel ionic polymer of Example 1, further proving the successful preparation of the novel ionic polymer of Example 1.

[0068] The performance of Zn||I2 full cells assembled from ionic polymer solid electrolytes prepared in Example 1 and Comparative Examples 1-2 was tested and compared, and the results are as follows: Figures 3-6 As shown.

[0069] Figure 3 The results show that the novel ionic polymer solid electrolyte system containing active nitrogen cations and bromide anions exhibits the highest ionic conductivity (1.64 mS / cm) at 25°C for both Example 1 and Comparative Examples 1 and 2. -1 The ionic conductivity of solid-state polymer electrolyte systems containing only nitrogen ions or bromide ions is 1.40 mS / cm, respectively. -1 and 0.82 mS cm -1 The above results indicate that the synergistic effect of the two ions, especially the interaction between the nitrogen cation and the zinc salt anion, promotes the transport of zinc ions, significantly enhances the ionic conductivity of the polymer solid electrolyte, and thus ensures the conversion reaction kinetics of the zinc-iodine battery.

[0070] Figure 4The cycling performance of the Zn‖Zn symmetric battery assembled using the ionic polymer solid electrolyte prepared in Example 1 of this invention was evaluated. The results show that when using an ionic polymer solid electrolyte containing both active nitrogen ions and bromide anions, the cycling performance at 5 mA cm⁻¹ is significantly improved. -2 The symmetric battery can cycle stably for over 2800 hours at the specified current density and is still cycling stably. These results demonstrate that a solid electrolyte with a dual-ion synergistic effect can effectively avoid the side reactions such as hydrogen evolution and corrosion that easily occur in zinc metal in aqueous electrolytes due to thermodynamic instability. Furthermore, it is verified that nitrogen ions can interact with zinc salt anions, promoting zinc ion transport, stabilizing the zinc anode, and thus improving the cycle life of the zinc-iodine battery.

[0071] Figure 5 Cyclic voltammetry curves of Zn||I2 full cells assembled using the ionic polymer solid electrolytes prepared in Example 1 and Comparative Examples 1-2 of this invention are shown. The results indicate that both the novel ionic polymer solid electrolyte and the ionic polymer solid electrolyte containing only bromide anions exhibit two pairs of clear redox peaks, while the ionic polymer solid electrolyte containing only nitrogen ions shows only one pair of redox peaks. This suggests that the presence of halide anions can promote the I2 oxidation at the I2 cathode. - / I 0 / I + Four-electron conversion reaction. In particular, the use of novel ionic polymers exhibits larger redox peak areas, indicating a higher theoretical specific capacity, further demonstrating the important role of the synergistic effect of the two ions in activating the four-electron conversion reaction and increasing capacity.

[0072] Figure 6 The figures show the charge-discharge curves of Zn||I₂ full cells assembled with the ionic polymer solid electrolytes prepared in Example 1 and Comparative Examples 1 and 2 of this invention. The results show that two distinct charge-discharge plateaus exist when using the novel ionic polymer solid electrolyte and the ionic polymer solid electrolyte containing only bromide anions, while only one charge-discharge plateau appears when using the ionic polymer solid electrolyte containing only nitrogen ions. This corresponds to the cyclic voltammetry curves, further demonstrating the importance of halide anions in achieving I₂. - / I 0 / I + The four-electron conversion reaction plays a crucial role. Further observation reveals that when using a novel ionic polymer solid electrolyte, the discharge specific capacity can reach 353 mAh g at a current density of 0.2 A / g. -1 However, when using an ionic polymer solid electrolyte containing only nitrogen ions, the specific capacity is only 170 mAh g. -1 This further illustrates that halogen anions can significantly improve the specific capacity of the I2 cathode, thereby increasing the energy density of zinc-iodine batteries.

[0073] Figure 7 The long-cycle performance of the Zn‖I2 full cell assembled using the ionic polymer solid electrolyte prepared in Example 1 of this invention was investigated. The results show that when using an ionic polymer solid electrolyte containing both active nitrogen ions and bromide anions, stable cycling for 5300 cycles is achieved at a high current density of 4 A / g, with a capacity retention of 81%. These results demonstrate that through precise design of the polymer molecular structure and functional groups, it is possible to simultaneously achieve I… - / I 0 / I + The efficient excitation and stabilization of the four-electron reaction, the effective suppression of polyiodide shuttle, and the rapid promotion of zinc ion transport and deposition kinetics ensure the high specific capacity, long cycle stability, and high rate performance of zinc-iodine batteries.

[0074] Example 2

[0075] The difference between this embodiment and Example 1 is that monomer I in step 1) is changed to p-1,4-dibromomethylbenzene, while the remaining steps are the same as in Example 1, resulting in the novel ionic polymer solid electrolyte of this embodiment.

[0076] Example 3

[0077] The difference between this embodiment and Example 1 is that monomer I in step 1) is adjusted to 1,3,5-trichloromethylbenzene, while the remaining steps are the same as in Example 1, resulting in the novel ionic polymer solid electrolyte of this embodiment.

[0078] Example 4

[0079] The difference between this embodiment and Example 1 is that the nitrogen-containing compound II in step 1) is adjusted to 1,3,5-tris(1H-imidazol-1-yl)benzene, while the remaining steps are the same as in Example 1, resulting in the novel ionic polymer solid electrolyte of this embodiment.

[0080] Example 5

[0081] The difference between this embodiment and Example 1 is that the nitrogen-containing compound II in step 1) is adjusted to 1,4-bis(1H-imidazol-1-yl)pyridazine, while the remaining steps are the same as in Example 1, resulting in the novel ionic polymer solid electrolyte of this embodiment.

[0082] Example 6

[0083] The difference between this embodiment and Embodiment 1 is that the ratio of the novel ionic polymer to polyvinylidene fluoride (PVDF) in step 2) is adjusted to 1:20, while the remaining steps are the same as in Embodiment 1, to obtain the novel ionic polymer solid electrolyte of this embodiment.

[0084] The ionic conductivity, specific capacity, and cycle performance of the electrolytes in Examples 1-6 were tested, and the results are shown in Table 1.

[0085] Table 1. Performance comparison of electrolytes in Examples 1-6

[0086]

[0087] It can be seen that the novel ionic polymers prepared in Examples 1-6 of this invention all exhibit high ionic conductivity and are capable of delivering high specific capacity and ultra-long cycle life. These results indicate that the simultaneous introduction of positive and negative ions into the structure plays a crucial role in the performance of polymer solid electrolytes. Although changing the type of monomer I containing active halogens, the type of nitrogen-containing compound II with strong nucleophilicity, and the amount of ionic polymer added inevitably leads to changes in electrolyte properties and battery electrochemical behavior, the overall performance is still superior to comparative examples 1-2. This demonstrates that retaining active nitrogen positive ions or halide negative ions in the ionic polymer can leverage the synergistic effect of dual ions in the polymer solid electrolyte, achieving an I2 cathode based on I... - / I 0 / I + High specific capacity and ultra-long cycle stability of the four-electron conversion reaction.

[0088] In summary, this invention addresses the challenges of conventional polymer solid electrolytes in simultaneously achieving high ionic conductivity and selective ion transport capabilities, as well as the lack of active control over the redox reaction pathway of iodine. It proposes a dual-ion synergistic modification strategy. Specifically, halide anions act as a redox medium and stabilizer, effectively exciting and stabilizing the I₂ cathode. - / I 0 / I +The four-electron conversion reaction significantly increases the theoretical capacity of the I2 cathode to twice that of the traditional two-electron pathway, thereby greatly improving the battery's energy density. Secondly, the novel ionic polymer electrolyte membrane exhibits excellent ion selectivity, effectively blocking the shuttle of polyiodides and mitigating self-discharge, thus enhancing the reversibility of the electrochemical reaction and the battery's cycle stability. Furthermore, the active nitrogen ions in the polymer backbone can reversibly bind with zinc salt anions, not only promoting zinc salt dissociation and increasing the bulk ionic conductivity of the polymer solid electrolyte, but also reducing the migration barrier of zinc ions at the zinc metal anode interface, achieving uniform and rapid zinc metal deposition / stripping, inhibiting dendrite growth, and thus improving battery cycle life and safety. The novel ionic polymer electrolyte provided by this invention overcomes the single-function limitation of traditional polymer electrolytes as ion conductors. Through the synergistic mechanism of halide anion-catalyzed multi-electron reactions, polymer membrane selective ion conduction, and nitrogen ion-promoted zinc ion transport, it achieves multiple regulation of battery reaction pathways, interface stability, and transport kinetics, providing a novel solution for constructing high-capacity, long-life, and high-safety zinc-iodine batteries.

[0089] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A novel ionic polymer solid electrolyte, which is obtained by solution casting from a novel ionic polymer, a polymer matrix, an organic solvent, and a zinc salt; Its features are, The novel ionic polymer is formed by polymerizing a monomer I containing an active halogen and a nitrogen-containing compound II with strong nucleophilicity. The monomer I containing an active halogen and the nitrogen-containing compound II with strong nucleophilicity react according to the molar ratio of nitrogen cation to halide anion. The monomer I containing an active halogen is one or more of the following: 1,4-dibromomethylbenzene, 1,3-dibromomethylbenzene, 1,3,5-tribromomethylbenzene, 1,2,4,6-tetrabromomethylbenzene, 1,4-dichloromethylbenzene, 1,3-dichloromethylbenzene, 1,3,5-trichloromethylbenzene, 1,2,4,6-tetrachloromethylbenzene, 1,3,5-tris[4-(bromomethyl)phenyl]benzene, 2,4,6-tris(4-(bromomethyl)phenyl)-1,3,5-triazine, 1,4-bis(bromomethyl)naphthalene, 2,6-bis(bromomethyl)naphthalene, 2,7-bis(bromomethyl)naphthalene, and 4,4'-bis(bromomethyl)biphenyl. The strongly nucleophilic nitrogen-containing compound II is one or more of the following: 1,4-bis(1H-imidazol-1-yl)benzene, 1,3-bis(1H-imidazol-1-yl)benzene, 1,3,5-tris(1H-imidazol-1-yl)benzene, 1,4-bis(1H-imidazol-1-yl)pyridazine, 1,3-bis(1H-imidazol-1-yl)pyridazine, 1,3,5-tris(1H-imidazol-1-yl)pyridazine, 2,4,6-tris(1H-imidazol-1-yl)-1,3,5-triazine, and 2,4,6-tris[4-(1H-imidazol-1-yl)-phenyl]-1,3,5-triazine. The novel ionic polymer accounts for 3% to 20% of the mass percentage of the polymer solid electrolyte.

2. The novel ionic polymer solid electrolyte according to claim 1, characterized in that, The monomer I containing an active halogen and the nitrogen-containing compound II with strong nucleophilicity are polymerized in a reaction solvent, which is one or more of N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), dichloromethane (DCM), toluene (Tol), and acetonitrile (ACN), and its mass is 8 to 15 times the total weight of the monomer I containing an active halogen and the nitrogen-containing compound II with strong nucleophilicity.

3. The novel ionic polymer solid electrolyte according to claim 1, characterized in that, The zinc salt is one or more of zinc sulfate (ZnSO4), zinc bis(TFSI)2, zinc trifluoromethanesulfonate (Zn(OTf)2), zinc chloride (ZnCl2), and zinc perchlorate (Zn(ClO4)2), and the zinc salt accounts for 10% to 50% of the polymer solid electrolyte by mass.

4. The novel ionic polymer solid electrolyte according to claim 1, characterized in that, The polymer matrix is ​​one or more of polyethylene oxide (PEO), polyvinylidene fluoride (PVDF), polyacrylamide (PAM), polyacrylonitrile (PAN), and polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP).

5. The novel ionic polymer solid electrolyte according to claim 1, characterized in that, The organic solvent is one or more of N,N-dimethylformamide (DMF), acetonitrile (ACN), N,N-dimethylacetamide (DMAc), dimethyl sulfoxide (DMSO), and ionic liquids.

6. A method for preparing a novel ionic polymer solid electrolyte according to any one of claims 1-5, characterized in that, Includes the following steps: Step 1: Polymerize monomer I containing active halogens and nitrogen-containing compound II with strong nucleophilicity in a reaction solvent to form a novel ionic polymer; Step 2: Place the novel ionic polymer, polymer matrix and zinc salt from Step 1 into an organic solvent and stir thoroughly to disperse them evenly, so as to obtain a uniform and stable composite electrolyte slurry, which is the film-forming solution. Step 3: Pour the film-forming solution from Step 2 into a mold, and after drying and demolding, obtain a novel ionic polymer solid electrolyte.

7. The method for preparing the novel ionic polymer solid electrolyte according to claim 6, characterized in that, The novel ionic polymer solid electrolyte obtained in step 3 has a film thickness of 140 μm to 300 μm.

8. The method for preparing the novel ionic polymer solid electrolyte according to claim 6, characterized in that, The reaction conditions for polymerization in the reaction solvent in step 1 are as follows: stirring at 100°C for 24 h under a nitrogen atmosphere, washing three times with DMF and acetonitrile after the reaction is completed, and drying at 60°C for 24 h; the stirring time in step 2 is 12 h; the drying conditions in step 3 are drying at 60°C for 8 h.

9. The application of the novel ionic polymer solid electrolyte according to any one of claims 1-5 in the preparation of a zinc-iodine battery with a four-electron conversion reaction.

10. The application according to claim 9, characterized in that, The zinc-iodine battery with the four-electron conversion reaction includes a novel ionic polymer solid electrolyte, and also includes a zinc metal anode and an activated carbon-supported I2 cathode.

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