Cationic organic framework, preparation method and application of cationic organic framework in high-voltage zinc-iodine battery

Abstract

The invention relates to the technical field of electrochemistry, in particular to a cationic organic framework, a preparation method and application of the cationic organic framework in a high-voltage zinc-iodine battery, and the cationic organic framework comprises two independent synthesis ways: a Schiff base reaction synthesis method forms an imine bond framework with regular pore channels by using aromatic aldehyde and amine monomers; a carbon-carbon double bond bridging framework is constructed by an aromatic compound containing an aldehyde group and an active methylene through a Cnovengil reaction synthesis method, and the conductivity is excellent. When used as a positive electrode material, the material can load iodine and inhibit shuttling of polyiodide through strong electrostatic interaction, and also can catalyze four-electron conversion to improve capacity and energy density; when the material is used as a diaphragm modified material, polyiodide can be screened through regular pore channels, zinc ion transmission is guided through groups to inhibit dendritic crystals, and the battery performance is optimized. The assembled zinc-iodine battery can stably circulate for 40000 times in a low-temperature environment of-5 DEG C and at the current density of 5 A.g <-1 >, the capacity retention rate can still reach 86%, the circulation stability is excellent, and diversified schemes are provided for high-performance energy storage devices.

Description

Technical Field

[0001] This invention relates to the field of electrochemical technology, specifically to a cationic organic framework, its preparation method, and its application in high-voltage zinc-iodine batteries. Background Technology

[0002] In today's increasingly intelligent development trend, the efficient utilization of renewable energy has become a hot topic in scientific research. However, renewable energy sources such as wind, solar, and tidal power are often affected by environmental factors, making it difficult to provide consistent and stable energy output. To address this limitation, researchers are working to develop rechargeable battery systems capable of providing stable energy output. Currently, rechargeable batteries are mainly lithium-ion batteries. However, due to the limited and high cost of lithium resources, there is a growing demand for large-scale, highly safe, and low-cost aqueous energy storage batteries. Zinc-iodine batteries are an important candidate for aqueous energy storage systems due to the high theoretical capacity of zinc anodes (820). Iodine cathodes have attracted much attention due to their abundant and inexpensive resources, as well as the high safety of aqueous electrolytes. However, their practical application faces three major challenges: firstly, the polyiodide shuttle effect, and secondly, the formation of soluble iodides during charging and discharging. , Species readily migrate between the positive and negative electrodes, leading to loss of active material and decreased coulombic efficiency; secondly, zinc dendrite growth occurs in aqueous electrolytes. Uneven deposition can lead to dendrite formation, which may penetrate the membrane and cause a short circuit, severely shortening cycle life; thirdly, the four-electron reaction kinetics are sluggish, while traditional iodine cathodes mainly rely on two-electron reactions. The theoretical capacity is only 211. And four-electron reactions ( Although it has a higher capacity, it is limited by a high reaction energy barrier.

[0003] Organic frameworks, as a novel class of porous crystalline materials, have shown great potential in the field of energy storage due to their structural designability, high specific surface area, and chemical stability. Traditional organic frameworks form an ordered framework by covalently linking aromatic monomers, but their neutral surface charge limits their ability to adsorb and regulate polar substances.

[0004] In view of the above-mentioned defects, the inventors of this invention have finally obtained this invention after a long period of research and practice. Summary of the Invention

[0005] The purpose of this invention is to solve the problem that traditional organic frameworks form an ordered skeleton by covalently connecting aromatic monomers, but their neutral surface charge limits their ability to adsorb and regulate polar substances. This invention provides a cationic organic framework, a preparation method, and its application in high-voltage zinc-iodine batteries.

[0006] In order to achieve the above object, the application discloses a preparation method of cationic organic framework, comprising the following steps:

[0007] S1, mixing organic monomer M1, organic monomer M2 or organic monomer M3, solvent and catalyst, adding into a heat-resistant glass tube, ultrasonic dispersion, liquid nitrogen freezing, vacuumizing, thawing, repeating 3-5 times, finally flame sealing, placing in a drying box at 120 DEG C for heating reaction for 3 days, collecting the precipitate;

[0008] S2, Soxhlet extraction treatment of the precipitate obtained in step S1 with tetrahydrofuran and dichloromethane mixed solvent for 6-24 hours, then vacuum drying at 60 DEG C-80 DEG C for 6-12 hours, obtaining the cationic organic framework.

[0009] In the step S1, the organic monomer M1 is any one of the following structures:

[0010] 、 、 、 、 、 、 、 、 ;

[0011] In the formula, X is any one of H, OH, OCH3, Cl, Br and I.

[0012] In the step S1, the organic monomer M2 is any one of the following structures:

[0013] 、 、 、 、 、 ;

[0014] In the formula, X is any one of Cl, Br and I.

[0015] In the step S1, when the reactant is the organic monomer M2, the solvent is mesitylene and dioxane, the catalyst is acetic acid, the volume ratio of mesitylene, dioxane and acetic acid is 1:(1-3):(0.3-0.5), and the molar ratio of the organic monomer M1 and the organic monomer M2 is 1:(1.2-1.8).

[0016] In the step S1, the organic monomer M3 is any one of the following structures:

[0017] 、 、 、 、 、 ;

[0018] wherein X is any one of Cl, Br and I.

[0019] In the step S1, when the reactant is the organic monomer M3, the solvent is o-dichlorobenzene, n-butanol and water, the catalyst is 4-dimethylaminopyridine, the volume ratio of o-dichlorobenzene, n-butanol and water is 1: (1-1.5): (0.05-0.1), and the molar ratio of the organic monomer M1, the organic monomer M3 and 4-dimethylaminopyridine is 1: (1-1.8): (9-10).

[0020] The application further discloses the cationic organic framework prepared by the preparation method.

[0021] The application further discloses application of the cationic organic framework in a high-voltage zinc-iodine battery, and the cationic organic framework is used in the high-voltage zinc-iodine battery by being made into a cationic organic framework modified diaphragm or a cationic organic framework iodine-loaded positive electrode material.

[0022] The preparation method of the cationic organic framework modified diaphragm is specifically as follows: cationic organic framework material, conductive agent Super P and adhesive polyvinylidene fluoride are ground and mixed uniformly according to a mass ratio of (6-8):(1-3):1, then a proper amount of N-methylpyrrolidone is added and stirred for 5-7 hours to obtain a slurry, the slurry is coated on glass fiber by scraping, spin coating or drop coating, and then vacuum drying is carried out at 40-80 DEG C for 10-20 hours to obtain the cationic organic framework modified diaphragm.

[0023] Alternatively, the cationic organic framework material and Super P are ground and mixed uniformly according to a mass ratio of (6-9):(1-4), then ethanol is added and ultrasonic treatment is carried out for 6 hours to prepare a solution, the solution is sprayed on glass fiber by using a spray gun, and then vacuum drying is carried out at 40-80 DEG C for 10-20 hours to obtain the cationic organic framework modified diaphragm.

[0024] The preparation method of the positive electrode material of the cationic organic framework loaded with iodine is specifically as follows: the cationic organic framework material and iodine are uniformly mixed by grinding in a mass ratio of 1: (1-1.2), and then sealed and placed in a 120 DEG C drying box for 6 hours; then taken out and cooled; after cooling to room temperature, the mixed material of the cationic organic framework material and iodine is mixed with conductive agent ketjen black in a mass ratio of 7:2; after uniform mixing, the mixed material of the cationic organic framework material, iodine and ketjen black is mixed with a binder polytetrafluoroethylene in a mass ratio of 9:1; then 10-20 muL of isopropyl alcohol is added to roll into a film-shaped material, and placed in a 40 DEG C drying box for 10 hours; finally, the film-shaped material is cut into a film-shaped material with 5-10 muL of isopropyl alcohol, and the positive electrode material of the cationic organic framework loaded with iodine is obtained by rolling on an aluminum mesh. -2 The film-shaped material is cut into a film-shaped material with 5-10 muL of isopropyl alcohol, and the positive electrode material of the cationic organic framework loaded with iodine is obtained by rolling on an aluminum mesh.

[0025] The cationic organic framework is designed to introduce imidazolium, quaternary ammonium group and other cationic sites in the skeleton, realizes accurate charge control, and at the same time retains the porous structure and conjugate characteristics of the organic framework, laying a foundation for its application in electrochemical devices.

[0026] As a positive electrode material, the rich positive charge sites can efficiently adsorb polyiodide anions through strong electrostatic interaction, thereby inhibiting the shuttle effect from the root; at the same time, the conjugated skeleton provides a fast electron transport channel, and the coordination between the cationic sites and iodine species can reduce the four-electron reaction energy barrier, promote The efficient conversion of , significantly improves the positive electrode capacity and energy density. In addition, the regular pore structure of the organic framework can confine the iodine species, avoiding agglomeration and shuttle, further optimizing the reaction kinetics.

[0027] As a separator modification material, the ordered porous structure of the cationic organic framework can block the migration of polyiodide through size screening effect, and the positive charge on the surface can guide transport in a directional manner, inhibiting ion concentration polarization; the weak coordination between the cationic sites and can regulate the zinc ion deposition behavior, avoiding dendrite growth and prolonging the cycle life of the battery. Compared with traditional separator materials, the cationic organic framework modified separator has ion selectivity and interface stability, and can maintain excellent performance under high current density.

[0028] The beneficial effects of the present application compared with the prior art are:

[0029] 1. The present application provides two preparation methods of cationic organic frameworks, which can accurately control the structural characteristics of the cationic organic framework according to different performance requirements. The Schiff base reaction focuses on building a high-stability imine bond skeleton, and the Knovenagel reaction strengthens the sp² hybridization carbon conjugated conductivity, realizing the directional design of material structure and function;

[0030] 2. When the cationic organic framework provided by this invention is used as a positive electrode material, the positively charged sites of the cationic organic framework selectively adsorb polyiodides through strong electrostatic interactions. / This significantly reduces its migration rate in the electrolyte. Simultaneously, the regular porous structure spatially confines iodine species, reducing the loss of active material and solving the capacity decay problem caused by the shuttle effect in traditional zinc-iodine batteries.

[0031] 3. When the cationic organic framework provided by this invention is used as a membrane material, it blocks polyiodides through size sieving, and its surface positive charge can be directionally guided. Transport reduces ion concentration polarization. Furthermore, cation sites and... The weak coordination effect can regulate zinc deposition kinetics, inhibit dendrite growth, and significantly improve battery cycle stability. It can maintain a long cycle life even at high current density. It also provides four membrane preparation methods, which are scientifically designed, simple in process, and low in cost.

[0032] 4. The conjugated framework of the cationic organic structure provides an efficient electron transport pathway. The coordination between cation sites and iodine species can lower the energy barrier of the four-electron reaction, breaking through the capacity limitation of the traditional iodine cathode's single-electron reaction. By activating high-capacity four-electron reactions, the energy density of zinc-iodine batteries is significantly improved, supporting the demand for high-power energy storage. Attached Figure Description

[0033] Figure 1 (a) Schematic diagram of the COF-Cl structure prepared in Example 1, (b) powder X-ray diffraction pattern and (c) Fourier transform infrared spectrum;

[0034] Figure 2 (a) Scanning electron microscopy (SEM) image and (b) Transmission electron microscopy (TEM) image of COF-Cl prepared in Example 1;

[0035] Figure 3 (a) CV spectrum and (b) impedance spectrum of the zinc-iodine battery with COF-Cl modified separator prepared in Example 1;

[0036] Figure 4 The zinc-iodine battery (a) prepared for Example 1 was tested at 10 A g. -1 (a) Comparison of long-cycle performance between COF-Cl modified separator and blank glass fiber (GF) at current density; (b) Comparison of rate performance between COF-Cl modified separator and GF; (c) Charge-discharge curve of COF-Cl modified separator; (d) Charge-discharge curve of GF.

[0037] Figure 5The zinc-iodine battery (a) prepared for Example 1 was tested at 5 A g. -1 (a) Self-discharge performance of COF-Cl modified membrane at a current density of (b) High iodine loading performance of COF-Cl modified membrane; (c) Low temperature environment of -5 °C and 5 A g -1 Long-cycle performance of COF-Cl modified membrane at current density;

[0038] Figure 6 The zinc-iodine battery prepared for Example 2 was tested at 2 A g. -1 Cyclic performance at current density;

[0039] Figure 7 Here are (a) a schematic diagram of the structure of the LD-COF prepared in Example 3, (b) a powder X-ray diffraction pattern, and (c) a zinc-iodine battery at 2 A g. -1 Cyclic plot at current density;

[0040] Figure 8 Here are (a) a schematic diagram of the structure of the TF-COF prepared in Example 4, (b) a powder X-ray diffraction pattern, and (c) a zinc-iodine battery at 2 A g. -1 Cyclic plot at current density;

[0041] Figure 9 The zinc-iodine battery prepared for Example 5 was tested at 2 A g. -1 Cyclic performance at current density;

[0042] Figure 10 The zinc-iodine battery prepared for Example 6 was tested at 10 A g. -1 Cyclic performance at current density;

[0043] Figure 11 This is a schematic diagram of the structure of the DB-COF material prepared in Example 7;

[0044] Figure 12 Powder X-ray diffraction pattern (a) of DB-COF prepared in Example 7 and zinc-iodine battery at 2 A g -1 Cyclic plot at current density (b);

[0045] Figure 13 Cyclic performance comparison diagram of LD-COF prepared by Schiff base reaction in Example 3 and DB-COF prepared by Knovengel reaction in Example 7 as separator materials in zinc-iodine batteries;

[0046] Figure 14 The graph shows the cycling performance of LD-COF prepared by the Schiff base reaction in Example 3 and DB-COF prepared by the Knovengel reaction in Example 3 as positive electrode materials in zinc-iodine batteries. Detailed Implementation

[0047] The above-mentioned and other technical features and advantages of the present invention will be described in more detail below with reference to the accompanying drawings.

[0048] Example 1

[0049] Application of cationic organic frameworks (COF-Cl) prepared by Schiff base reaction as membrane materials in four-electron zinc-iodine batteries:

[0050] Step 1: Weigh 21 mg of trialdehyde phloroglucinol as organic monomer M1 and 59.1 mg of ethidium bromide as organic monomer M2. Place organic monomer M1 and organic monomer M2 into a heat-resistant glass tube. Add 0.75 mL of mesitylene, 0.75 mL of dioxane, and 0.3 mL of 6 mol·L⁻¹ to the glass tube. -1 A mixed solution of acetic acid was ultrasonically dispersed until homogeneous; then frozen in liquid nitrogen, vacuum-sealed, and thawed to room temperature, repeated three times. Finally, the mixture was flame-sealed and heated in a 120 °C drying oven for 3 days. The precipitate was collected and subjected to Soxhlet extraction with a mixed solution of tetrahydrofuran and dichloromethane for 24 hours, followed by vacuum drying at 80 °C for 6 hours. The resulting material was then treated with 1 mol·L⁻¹... -1 Hydrochloric acid was used for ion exchange for 72 h to remove the Br. - Replace with Cl - This yields a cationic organic framework material (COF-Cl).

[0051] The molecular structure of its material is as follows Figure 1 As shown in (a), the PXRD pattern ( Figure 1 (b) and FT-IR spectra ( Figure 1 (c) This demonstrates the successful preparation of the material, which possesses a complete crystal structure and multiple functional groups. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images of the COF-Cl material are shown below. Figure 2 (a) and Figure 2 As shown in (b), the porous and layered characteristics of COF materials can be seen.

[0052] Step 2: Weigh COF-Cl material, Super P, and polyvinylidene fluoride (PVDF) according to a mass ratio of 6:3:1, then add an appropriate amount of N-methylpyrrolidone (NMP), and stir at room temperature for 5-6 hours. The resulting slurry is then uniformly drop-coated onto glass fibers using a drop-coating method. Specifically, use a pipette to draw an equal amount of slurry (120 μL) each time and drop it onto pre-cut glass fibers with a diameter of 19 mm. Then, place the slurry in a vacuum drying oven at 80 ℃ for 10 hours to obtain a cationic organic framework modified membrane.

[0053] Subsequently, the modified separator or GF obtained in step two was applied to a four-electron zinc-iodine battery. Activated carbon / iodine composite cathode (50 wt.% iodine loading) was selected as the cathode material, zinc sheet was used as the anode, and the electrolyte was 2 M ZnSO4 + 0.5 M NH4Cl, thus assembling the zinc-iodine battery.

[0054] The CV spectrum of the modified diaphragm is as follows: Figure 3 As shown in (a), it exhibits two pairs of reversible redox peaks, corresponding to... as well as Through impedance spectroscopy ( Figure 3 (b) It can be seen that the zinc-iodine battery assembled with the modified separator has an impedance of only 52Ω, exhibiting rapid reaction kinetics. For example... Figure 4 As shown in (a), at 10 A g -1 At the specified current density, the modified zinc-iodine battery achieves a first-cycle discharge specific capacity of 212.4 mAh g⁻¹. -1 It is higher than the GF membrane's 204.1 mAh g. -1 After 2000 stable cycles, the COF-Cl membrane maintained a capacity retention of 87.1%, while the GF membrane maintained only 37.9%. Subsequently, rate performance was tested, and the CE value of the COF-Cl membrane was significantly better than that of the GF membrane. Figure 4 (b)). Furthermore, the COF-Cl membrane was tested at current densities of 1, 2, 5, and 10. The available frequencies are 287.3, 274.7, 252, and 228. Discharge specific capacity ( Figure 4 (c) These values ​​are all higher than those of the GF membrane under the same conditions, which are 264.9, 249.7, 228.2, and 211.9, respectively. Discharge specific capacity ( Figure 4 (d)). Subsequent performance tests of the modified membrane battery for practical applications, such as... Figure 5 As shown, Figure 5 (a) shows the battery's self-discharge test. After being fully charged and left to rest for 48 hours, it continued cycling, resulting in a capacity loss of only 4.3%, and subsequently maintained stable cycling performance, demonstrating excellent anti-self-discharge performance. Furthermore, in the high-load test, the positive electrode iodine loading reached 8 mg cm⁻¹. -2 and 12 mg cm -2 The battery can still cycle stably for 600 times, with an average coulombic efficiency of 99.3% and 98.6% ( ). Figure 5 (b)). At a low temperature of -5 °C and 5 A g -1 At a current density of [value missing], the modified battery can stably cycle 40,000 times with a capacity retention rate as high as 86%. Figure 5(c), which has very stable super-long cycle performance. As shown in Table 1, it still has great competitiveness compared with other four-electron zinc-iodine working.

[0055] The modified separator can effectively repel anions in polyiodide and promote the transmission of zinc ions, while also promoting the conversion of iodine between different valence states, effectively improving the cycle stability and capacity of the four-electron zinc-iodine battery, and also having great competitiveness in actual applications.

[0056] Example 2

[0057] Application of cationic organic framework (COF-Cl) prepared by Schiff base reaction as positive electrode material in four-electron zinc-iodine battery:

[0058] Step one: the preparation method of COF-Cl is consistent with step one in example 1.

[0059] Step two: according to the mass percentage of 1:1.2, the COF material and iodine obtained in step one are weighed, ground for 10 minutes, mixed uniformly, and then sealed into a 120°C drying box for 6 hours. Then take out and grind with KB according to the mass ratio of 7:2 for 10 minutes, so that they are mixed uniformly. After the mixing is completed, the mixed material and PTFE are rolled into a film shape according to the mass ratio of 9:1 and a small amount of isopropyl alcohol is added, and then placed in a 40°C drying box for 10 hours. After drying, the positive electrode material is obtained according to the mass ratio of 1 mg cm -2 (30wt.% iodine loading) is weighed and rolled onto an aluminum mesh with a small amount of isopropyl alcohol, and then the electrode piece is placed in a 40°C drying box for 3 hours to dry, thereby obtaining the cationic organic framework iodine-loaded positive electrode piece.

[0060] Then, the positive electrode obtained in step two is applied to the four-electron zinc-iodine battery. Glass fiber (GF) is selected as the separator material, zinc sheet as the negative electrode, and the electrolyte is 2 M ZnSO4+0.5 M NH4Cl, and the zinc-iodine battery is assembled. At a current density of 2 A g -1 , the specific capacity of the modified zinc-iodine battery reaches 312 mAh g -1 after the first cycle, and the capacity is as high as 241.6 mAh g -1 after stable cycling for 200 cycles, showing excellent cycle stability. The specific performance is shown in Figure 6 .

[0061] Example 3

[0062] Application of cationic organic framework (LD-COF) prepared by Schiff base reaction as separator material in four-electron zinc-iodine battery:

[0063] Step one: take 21 mg of tri-aldehyde phloroglucinol as organic monomer M1 and 36.6 mg of 6,6'-diamino-1,1'-diethyl-[3,3'-bipyridine]-1,1'-dication as organic monomer M2, put the organic monomer M1 and the organic monomer M2 into a heat-resistant glass tube, add 0.75 mL of mesitylene, 0.75 mL of dioxane, and 0.3 mL of a mixed solution of 6 mol / L acetic acid into the glass tube, and uniformly ultrasonically disperse; then freeze in liquid nitrogen, vacuumize, thaw to room temperature, repeat 3 times, finally flame seal, and place in a drying box at 120 ℃ to heat and react for 3 days, collect the precipitate, perform Soxhlet extraction treatment with a mixed solution of tetrahydrofuran and dichloromethane for 24 hours, and then vacuum dry at 80 ℃ for 6 hours, to obtain a cationic organic framework material (LD-COF).

[0064] The molecular structure of the material is shown in Figure 7 (a), and the PXRD spectrum is shown in Figure 7 (b), which exhibits a good COF crystal form.

[0065] Step two: take the LD-COF material and Super P and polyvinylidene fluoride (PVDF) according to a mass percentage of 6:3:1, then add an appropriate amount of N-methyl pyrrolidone (NMP), then stir on a stirring table at room temperature for 5-6 hours, and then uniformly drop coat the obtained slurry on glass fibers by using a pipette to drop coat an equal amount of slurry (100 μL) on the previously cut glass fibers each time, and then place in a vacuum drying box at 80 ℃ to dry for 10 hours, to obtain a cationic organic framework modified separator.

[0066] Subsequently, the modified separator or GF obtained in step two is applied to a four-electron zinc-iodine battery. An activated carbon / iodine composite positive electrode (50 wt.% iodine loading) is selected as a positive electrode material, a zinc sheet is used as a negative electrode, and an electrolyte is 2 M ZnSO4+0.2 M ZnBr2, to assemble a zinc-iodine battery. As shown in Figure 7 (c), the initial capacity of the modified zinc-iodine battery can reach 278.7 mAh g -1 at a current density of 2 A g -1 , and the capacity remains 283.2 mAh g -1 after 400 cycles.

[0067] Example 4

[0068] Application of a cationic organic framework (TF-COF) prepared by a Grignard reaction as a separator material in a four-electron zinc-iodine battery:

[0069] Step one: 2,4,6-tris(4-formylphenyl)-1,3,5-triazine 26 mg as organic monomer M1, 1-ethyl-2,4,6-trimethylpyridinium bromide 20.7 mg as organic monomer M3, 72.5 mg 4-dimethylaminopyridine as catalyst were weighed, and the organic monomer M1 and the organic monomer M3 and the catalyst were put into a heat-resistant glass tube; a mixed solution of 1 mL of n-butanol, 1 mL of o-dichlorobenzene, and 0.05 mL of deionized water was added to the glass tube, and ultrasonic dispersion was performed until uniform, then frozen in liquid nitrogen, vacuumed, thawed to room temperature, repeated 3 times, finally flame sealed, and placed in a drying box at 180 °C for heating reaction for 3 days, the precipitate was collected, treated with a Soxhlet extraction with a mixed solution of tetrahydrofuran and dichloromethane for 24 hours, and then vacuum dried at 80 °C for 6 hours, and the structure of the cationic organic framework (TF-COF) obtained is as shown in Figure 8 (a) and the PXRD pattern of (b) shows that the material has a complete crystal form. Figure 8

[0070] Step two: the COF material obtained in step one, Super P, and polyvinylidene fluoride (PVDF) were weighed in a mass ratio of 7:2:1, then an appropriate amount of N-methyl pyrrolidone (NMP) was added, and then stirred on a stirring table at room temperature for 5-7 h, the obtained slurry was dropped on the previously cut glass fiber with a diameter of 19 mm using a pipette gun to take an equal amount of slurry (120 μL) each time, and placed in a vacuum drying box at 80 °C for drying for 10 hours, to obtain a modified separator.

[0071] Subsequently, the modified separator obtained in step two was applied in a zinc-iodine battery. Activated carbon / iodine (50 wt.% iodine loading) was selected as the positive electrode, zinc sheet as the negative electrode, and 2 M ZnSO4 + 0.2 M ZnBr2 as the electrolyte, to assemble a zinc-iodine battery. At a current density of 2 Ag -1 , the initial capacity of the modified zinc-iodine battery can reach 289.2 mAh g -1 , and the capacity can reach 334.4 mAh g -1 after 200 cycles, and the performance is as shown in Figure 8 (c).

[0072] The cationic organic framework prepared by the Knoevenagel reaction has better conductivity than the cationic organic framework prepared by the reaction of the Schiff base, and the latter has more stable performance.

[0073] Example 5

[0074] Application of the cationic organic framework (TF-COF) prepared by the Knoevenagel reaction as a positive electrode material in a four-electron zinc-iodine battery:​

[0075] Step 1: The preparation method of TF-COF is the same as Step 1 in Example 4.

[0076] Step 2: The method for preparing the TF-COF iodine-loaded positive electrode is the same as step 2 in Example 2.

[0077] Subsequently, the positive electrode obtained in step two was applied to a four-electron zinc-iodine battery. Glass fiber was selected as the separator material, zinc sheet as the negative electrode, and the electrolyte was 2 M ZnSO4 + 0.2 M ZnBr2. The zinc-iodine battery was then assembled. (The last part, "2 A g," appears to be an unrelated instruction and is omitted from the translation.) -1 At a current density of [value missing], the modified battery achieved a first-cycle capacity of 325.1 mAh g. -1 After 240 cycles, the capacity is 327.9 mAh g. -1 It exhibits excellent cycle stability, and its cycle performance is as follows: Figure 9 As shown.

[0078] Example 6

[0079] The application of cationic organic frameworks (TF-COF) prepared by the Knovengel reaction as both cathode and separator materials in four-electron zinc-iodine batteries:

[0080] Step 1: The preparation method of TF-COF is the same as Step 1 in Example 4.

[0081] Step 2: The method for preparing the TF-COF modified membrane is the same as step 2 in Example 4.

[0082] Step 3: The method for preparing the TF-COF iodine-loaded positive electrode is the same as step 2 in Example 2.

[0083] Subsequently, the separator obtained in step two and the positive electrode obtained in step three were applied to a four-electron zinc-iodine battery. A zinc sheet was used as the negative electrode, and the electrolyte was 2 M ZnSO4 + 0.2 M ZnBr2, thus assembling the zinc-iodine battery. At 2 A g... -1 At the specified current density, the modified battery achieved a first-cycle capacity of 338.4 mAh g⁻¹. -1， After 450 cycles, the capacity remains at 376.9 mAh g. -1 It exhibits very good cycle stability, and its cycle performance is as follows: Figure 10 As shown.

[0084] Example 7

[0085] Application of cationic organic frameworks (DB-COF) prepared by the Knovengel reaction as membrane materials in four-electron zinc-iodine batteries:

[0086] Step 1: Weigh 21.24 mg of (E)-4,4'-(ethylene-1,2-diyl)dibenzaldehyde as organic monomer M1, weigh 26.9 mg of 2,6-diethyl-1,5-dimethyl-3,7-dioxo-3,4,4a,7,8,8a-hexahydro-2,6-naphthidine-2,6-dication as organic monomer M3, and weigh 72.5 mg of 4-dimethylaminopyridine as catalyst. Place organic monomer M1, organic monomer M3, and catalyst into a heat-resistant glass tube. Add a mixed solution of 1 mL n-butanol, 1 mL o-dichlorobenzene, and 0.05 mL deionized water to the glass tube, sonicate to disperse evenly, then freeze in liquid nitrogen, vacuum, and thaw to room temperature. Repeat this process 3 times. Finally, seal with a flame and heat in a 180 ℃ drying oven for 3 days. Collect the precipitate and perform Soxhlet extraction with a mixed solution of tetrahydrofuran and dichloromethane for 24 hours. Then, at 80 ℃... The structure of the obtained cationic organic framework (DB-COF) is as follows: (Drying under vacuum at ℃ for 6 hours) Figure 11 As shown, Figure 12 (a) shows that the material has a complete crystal form.

[0087] Step 2: Weigh the COF material, Super P, and polyvinylidene fluoride (PVDF) obtained in Step 1 according to a mass ratio of 7:2:1. Then add an appropriate amount of N-methylpyrrolidone (NMP) and stir at room temperature for 5-7 hours. The resulting slurry is then coated using a drop-coating method. Using a pipette, an equal amount of slurry (120 μL) is dropped onto pre-cut glass fibers with a diameter of 19 mm. The coated fibers are then dried in a vacuum drying oven at 80 °C for 10 hours to obtain the modified diaphragm.

[0088] Subsequently, the modified separator obtained in step two was applied to a zinc-iodine battery. Activated carbon / iodine (50 wt.% iodine loading) was selected as the positive electrode, zinc sheet as the negative electrode, and the electrolyte was 2 M ZnSO4 + 0.2 M ZnBr2. The zinc-iodine battery was then assembled. -1 At current density, the modified zinc-iodine battery can achieve an initial capacity of 316 mAh g. -1 After 300 cycles, the capacity can reach 347.1 mAh g. -1 Performance such as Figure 12 As shown in (b).

[0089] The COF materials prepared by the two methods were compared, and their properties were as follows: Figure 13 , Figure 14 As shown, LD-COF prepared by the Schiff base reaction has good stability and can make the battery more stable when used as a separator material, especially at 10 Ag. -1 It can still achieve 238 mAh g at high current density.-1 the initial capacity, and still has a capacity of 206.5 mAh g -1 after 5000 cycles of stable circulation. The DB-COF material prepared by the Knovenagel reaction has a higher capacity and stable circulation at a small current density, such as 2 Ag -1 , but is not as good as the LD-COF prepared by the Schiff base reaction at a large current density, such as 10 A g -1 , which has an initial specific capacity of 205.8 mAh g -1 , and only has a capacity of 138.5 mAh g -1 after 4000 cycles of circulation.

[0090] The LD-COF and the DB-COF are used for iodine positive electrodes as carriers of iodine, and the DB-COF material prepared by the Knovenagel reaction is more excellent, because the COF material prepared by the reaction has better conductive performance than the Schiff base reaction, so that it can better play a role as a positive electrode material. At a current density of 10 A g -1 , the DB-COF@I2 has an ultrahigh specific capacity of 280.9 mAh g -1 , and still has a capacity of 259.5 mAh g -1 after 5000 cycles of stable circulation. In comparison, the LD-COF@I2 has an initial specific capacity of only 213.4 mAh g -1 , and has a capacity of 225.1 mAh g -1 after 5000 cycles of circulation.

[0091] The above only describes the preferred embodiments of the present application, which are merely illustrative in nature rather than limiting. It is understood by those skilled in the art that many changes, modifications, and even equivalents can be made to the present application within the spirit and scope defined by the claims of the present application, and all will fall within the protection scope of the present application.

Claims

1. A method of preparing a cationic organic framework, characterized by, Comprising the following steps: S1, mixing organic monomer M1, organic monomer M2 or organic monomer M3, solvent, catalyst, adding into heat-resistant glass tube, ultrasonic dispersion, then liquid nitrogen freezing, vacuumizing, thawing, repeating 3-5 times, finally flame sealing, placing in 120 ℃ drying box for heating reaction for 3 days, collecting precipitate; S2, using tetrahydrofuran and dichloromethane mixed solvent to treat the precipitate obtained in step S1 by Soxhlet extraction for 6-24 hours, then vacuum drying at 60 ℃-80 ℃ for 6-12 hours, obtaining cationic organic framework.

2. The method for preparing a cationic organic framework as described in claim 1, characterized in that, In the step S1, the organic monomer M1 is any one of the following structures: 、 、 、 、 、 、 、 、 ； Wherein, X is any one of H, OH, OCH3, Cl, Br and I.

3. The method for preparing a cationic organic framework as described in claim 1, characterized in that, In the step S1, the organic monomer M2 is any one of the following structures: 、 、 、 、 、 ； Wherein, X is any one of Cl, Br and I.

4. The method for preparing a cationic organic framework as described in claim 1, characterized in that, In the step S1, when the reactant is organic monomer M2, the solvent is mesitylene and dioxane, the catalyst is acetic acid, the volume ratio of mesitylene, dioxane and acetic acid is 1:(1-3):(0.3-0.5), and the molar ratio of organic monomer M1 and organic monomer M2 is 1:(1.2-1.8).

5. The method for preparing a cationic organic framework as described in claim 1, characterized in that, In the step S1, the organic monomer M3 is any one of the following structures: 、 、 、 、 、 ； Wherein, X is any one of Cl, Br and I.

6. The method for preparing a cationic organic framework as described in claim 1, characterized in that, In the step S1, when the reactant is organic monomer M3, the solvent is o-dichlorobenzene, n-butanol and water, the catalyst is 4-dimethylaminopyridine, the volume ratio of o-dichlorobenzene, n-butanol and water is 1:(1-1.5):(0.05-0.1), and the molar ratio of organic monomer M1, organic monomer M3 and 4-dimethylaminopyridine is 1:(1-1.8):(9-10).

7. A cationic organic framework prepared by the preparation method of any one of claims 1-6.

8. Use of the cationic organic framework of claim 7 in a high-voltage zinc-iodine battery, characterized in that, The cationic organic framework is applied in the high-voltage zinc-iodine battery by being made into a cationic organic framework modified separator or a cationic organic framework iodine-loaded positive electrode material.

9. Use of a cationic organic framework in a high-voltage zinc-iodine battery according to claim 8, characterized in that, The preparation method of the cationic organic framework modified separator is as follows: grinding and mixing cationic organic framework material, conductive agent Super P and adhesive polyvinylidene fluoride according to mass ratio (6-8):(1-3):1, then adding appropriate amount of N-methyl pyrrolidone and stirring for 5-7 hours to obtain slurry, coating the slurry on glass fiber by scraping, spin coating or drop coating, and then vacuum drying at 40 ℃-80 ℃ for 10-20 hours to obtain the cationic organic framework modified separator. Or, grinding and mixing cationic organic framework material and Super P according to mass ratio (6-9):(1-4), then adding ethanol and ultrasonic treating for 6 hours to prepare a solution, spraying the solution on glass fiber by spray gun, and then vacuum drying at 40 ℃-80 ℃ for 10-20 hours to obtain the cationic organic framework modified separator.

10. Use of a cationic organic framework in a high-voltage zinc-iodine battery according to claim 8, characterized in that, The preparation method of the cationic organic framework loaded iodine positive electrode material is specifically as follows: the cationic organic framework material and iodine element are uniformly mixed according to a mass ratio of 1:(1-1.2), and then sealed into a 120 DEG C drying box for 6 hours; then taken out and cooled; after cooling to room temperature, the mixed material of the cationic organic framework material and iodine element is mixed with conductive agent Ketjen black according to a mass ratio of 7:2; after uniform mixing, the mixed material of the cationic organic framework material, iodine element and Ketjen black is mixed with adhesive polytetrafluoroethylene according to a mass ratio of 9:1; then 10-20 mu L of isopropyl alcohol is added to roll into a film-shaped material, which is placed into a 40 DEG C drying box for 10 hours; finally, the film-shaped material is cut into a film-shaped material with 5-10 mu L of isopropyl alcohol, which is rolled on an aluminum mesh to obtain a cationic organic framework loaded iodine positive electrode material. -2 The preparation method of the cationic organic framework loaded iodine positive electrode material is specifically as follows: the cationic organic framework material and iodine element are uniformly mixed according to a mass ratio of 1:(1-1.2), and then sealed into a 120 DEG C drying box for 6 hours; then taken out and cooled; after cooling to room temperature, the mixed material of the cationic organic framework material and iodine element is mixed with conductive agent Ketjen black according to a mass ratio of 7:2; after uniform mixing, the mixed material of the cationic organic framework material, iodine element and Ketjen black is mixed with adhesive polytetrafluoroethylene according to a mass ratio of 9:1; then 10-20 mu L of isopropyl alcohol is added to roll into a film-shaped material, which is placed into a 40 DEG C drying box for 10 hours; finally, the film-shaped material is cut into a film-shaped material with 5-10 mu L of isopropyl alcohol, which is rolled on an aluminum mesh to obtain a cationic organic framework loaded iodine positive electrode material.

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