Chlorinated fullerene-based positive electrode material, and preparation method and application thereof

Abstract

The application discloses a kind of chlorinated fullerene-based positive electrode materials and its preparation method and application, and positive electrode material includes metal-organic framework material and filled in its pore channel chlorine and fullerene derivative.Metal-organic framework material is generated by metal-organic precursor and the reaction of containing triphenylene ligand.Metal-organic precursor is generated by containing imidazole ligand, chlorinated fullerene and the reaction of metal ion.In charge and discharge process, the pore structure of metal-organic framework material forms space confinement to charging product chlorine, and the strong electron acceptor characteristics of fullerene derivative forms chemical adsorption to discharge product chloride ion, realizes the double fixation of charging and discharging product.Metal-organic framework material skeleton contains triphenylene ligand with high electron delocalization performance, while metal-organic framework material pore fills conductive fullerene derivative, realizes the double promotion of positive electrode material conductivity, applied to aqueous zinc-chlorine battery, and also can effectively improve the cycle performance of positive electrode material.

Description

Technical Field

[0001] This invention relates to the field of cathode materials for aqueous zinc metal batteries, and in particular to a fullerene-based chlorinated cathode material, its preparation method, and its application. Background Technology

[0002] With the rapid development of new energy and energy storage technologies, secondary battery systems that are safe, low-cost, and environmentally friendly have gradually become a key focus of research and industrialization. Among them, aqueous zinc metal batteries, due to their use of aqueous electrolytes, abundant zinc resources, and environmental friendliness, possess advantages such as high intrinsic safety and low manufacturing costs, showing promising application prospects in the field of large-scale energy storage.

[0003] In aqueous zinc-metal batteries, the cathode material is one of the key factors determining the battery's energy density, rate performance, and cycle stability. Compared to traditional intercalation / deintercalation cathode materials, cathode systems based on halogen redox reactions, especially chlorine-based cathode systems, have higher theoretical reaction potentials and higher specific capacity potentials, and are expected to further improve the energy density of aqueous zinc-halogen batteries.

[0004] However, existing aqueous zinc-chlorine batteries still face many technical bottlenecks in their chlorine-based cathode systems, mainly including:

[0005] (1) During the charging process, chlorine gas is generated on the positive electrode side. Chlorine gas has strong volatility and corrosiveness and is prone to leakage, which not only leads to the loss of active materials and the reduction of coulombic efficiency, but also poses safety hazards to the internal structure of the battery and the external environment;

[0006] (2) During the discharge process, chloride ions are generated on the positive electrode side. Chloride ions have high mobility in aqueous electrolytes and are prone to diffusion and crosstalk, leading to the loss of positive electrode active material and the aggravation of side reactions;

[0007] (3) In the existing optimization strategies for chlorine-based cathode materials, there is a general lack of effective confinement and control mechanisms for chlorine gas and chloride ions, which makes it difficult to guarantee the structural stability and reversibility of the cathode material during long-term cycling.

[0008] (4) In the preparation process of chlorine-based cathode films, due to the generally low conductivity of existing chlorine-containing cathode materials, a large amount of conductive agent is usually required, which makes it difficult to apply to energy storage batteries with high energy density requirements.

[0009] For halogen redox reaction-type cathode systems, existing research has attempted to regulate the chlorine-containing charge-discharge products through methods such as confinement with porous materials, fixation with adsorbents, or structural encapsulation. Metal-organic framework materials, due to their advantages such as tunable pore structure and large specific surface area, have been applied to the cathode structure of aqueous zinc-iodine / bromine batteries (Nano-Micro Letters 2026, 18 (1), 238. DOI: 10.1007 / s40820-026-02068-0) and the cathode structure of lithium-iodine / bromine batteries in organic electrolyte systems (Joule 2023, 7 (3), 515-528. DOI: 10.1016 / j.joule.2023.02.010). However, metal-organic framework materials still have certain limitations when applied to the cathode of aqueous zinc-chlorine batteries. The main limitations are that their intrinsic electronic conductivity is generally poor and their confinement effect on chlorine gas / chloride ions is limited (Energy Materials 2024, 4 (4), 400040. DOI: 10.20517 / energymater.2024.12).

[0010] Therefore, in order to improve the cathode performance of aqueous zinc-chlorine batteries by utilizing metal-organic framework materials, it is urgent to construct a cathode material system that can have both high electron transport capability and effective confinement capability for chlorine / chloride ions during the material synthesis stage, so as to solve the problems of easy loss of chlorine-based active materials, insufficient reaction reversibility and poor cycle stability in the existing technology. Summary of the Invention

[0011] To address the problems of chlorine volatilization and escape, easy diffusion and crosstalk of chloride ions, insufficient confinement ability of the cathode material for charge and discharge products, and poor intrinsic conductivity in existing aqueous zinc-chlorine battery cathodes, this invention provides a chlorinated fullerene-based cathode material, its preparation method, and its applications. This chlorinated fullerene-based cathode material constructs a composite structure of a metal-organic framework (MOF) and chlorine and fullerene derivatives filled within its pores. The MOF's pore structure spatially confines the charging product chlorine, while the fullerene derivatives' electron acceptor properties chemically adsorb the discharge product chloride ions, thus achieving dual fixation of charge and discharge products. Simultaneously, the MOF framework contains triphenylene-containing ligands with high electron delocalization performance, and the MOF's pores are filled with conductive fullerene derivatives, thereby achieving a dual improvement in the cathode material's conductivity. Overall, this improves the reversibility of the cathode reaction in aqueous zinc-chlorine batteries and enhances their cycle performance.

[0012] The present invention achieves the above objectives through the following technical solutions:

[0013] A fullerene-based cathode material, characterized in that the cathode material comprises a metal-organic framework material and chlorine gas and fullerene derivatives filling its pores;

[0014] The metal-organic framework material is generated by reacting a metal-organic precursor with a triphenylene-containing ligand, wherein the triphenylene-containing ligand includes hexahydroxytriphenylene; the metal-organic precursor is generated by reacting an imidazole-containing ligand, a fullerene chloride, and a metal ion, wherein the imidazole-containing ligand includes 2-methylimidazole, and the metal ion includes zinc ions.

[0015] The pore structure of the metal-organic framework material spatially confines the charging product chlorine gas, while the electron acceptor properties of the fullerene derivative chemically adsorb the discharging product chloride ions, thereby achieving dual immobilization of the charging and discharging products. The molecular formula of the fullerene derivative is: C x x is 60, 70, 76, 78 or 84;

[0016] The metal-organic framework contains triphenylene ligands with high electron delocalization performance, and the channels of the metal-organic framework are filled with conductive fullerene derivatives, thereby achieving a dual improvement in the conductivity of the cathode material.

[0017] Furthermore, the molecular formula of the fullerene chloride is: C x Cl y x is 60, 70, 76, 78 or 84, and the ratio of y to x is 0.1 to 0.5.

[0018] A method for preparing a fullerene-based cathode material includes the following steps:

[0019] Step 1: Dissolve fullerene chloride uniformly in toluene to form a fullerene chloride solution; dissolve 2-methylimidazole uniformly in methanol to form a 2-methylimidazole solution; add the fullerene chloride solution to the 2-methylimidazole solution to form a fullerene chloride / 2-methylimidazole mixed solution;

[0020] Step 2: Dissolve zinc acetylacetonate in methanol to form a zinc acetylacetonate solution;

[0021] Step 3: Add the fullerene chloride / 2-methylimidazole mixed solution from Step 1 to the zinc acetylacetone solution from Step 2 to form a precursor reaction solution;

[0022] Step 4: After the set reaction time, the solid-phase precipitate product and the liquid-phase solution in the precursor reaction solution are separated. The obtained solid-phase precipitate product is a metal-organic precursor.

[0023] Step 5: Wash and dry the metal-organic precursor with methanol, and then disperse the metal-organic precursor in water to form a metal-organic precursor dispersion.

[0024] Step 6: Dissolve hexahydroxytriphenylene in ethanol to form a hexahydroxytriphenylene solution, and then add the hexahydroxytriphenylene solution to the metal-organic precursor dispersion to form a metal-organic precursor / hexahydroxytriphenylene mixed solution;

[0025] Step 7: After the set reaction time, separate the solid crystals and reaction solution in the aforementioned metal-organic precursor / hexahydroxytriphenylene mixed solution;

[0026] Step 8: Wash the solid crystals with water and acetone, and then heat the solid crystals at a set temperature and time to obtain the fullerene-based cathode material.

[0027] Furthermore, in step one, the concentration of fullerene chloride in the mixed solution is 0.001~1 mol / L, the concentration of 2-methylimidazole in the mixed solution is 0.001~1 mol / L, and the molar ratio of fullerene chloride to 2-methylimidazole in the mixed solution is 1:1~1:10.

[0028] Furthermore, in step two, the concentration of the zinc acetylacetone solution is 0.01~10 mol / L.

[0029] Furthermore, in step three, the molar ratio of zinc acetylacetonate to 2-methylimidazole in the precursor reaction solution is 1:5 to 1:60.

[0030] Furthermore, the reaction time set in step four is 2~128 h, and the reaction time set in step seven is 2~128 h.

[0031] Furthermore, in step five, the mass concentration of the metal-organic precursor dispersion is 2-50 mg / mL, and / or in step six, the mass concentration of the hexahydroxytriphenylene solution is 2-50 mg / mL, and the mass ratio of the metal-organic precursor to hexahydroxytriphenylene in the metal-organic precursor / hexahydroxytriphenylene mixed solution is 1:1 to 1:5.

[0032] Furthermore, in step eight, the temperature is set to 100~150℃ and the time is set to 12~120 h.

[0033] An aqueous zinc-chlorine battery based on a fullerene-based cathode material includes a positive electrode, a negative electrode, an electrolyte, and a separator, wherein the positive electrode is a fullerene-based cathode material.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] 1. Construction of the conductive framework. In this invention, during the synthesis of the metal-organic precursor, a chlorinated fullerene derivative with strong electron acceptor ability is introduced, allowing it to interact with imidazole-containing ligands. This regulates the nucleation and growth behavior of the metal-organic precursor, inducing the formation of a metal-organic precursor composed of two-dimensional nanosheets. The metal-organic precursor composed of two-dimensional nanosheets undergoes a ligand conversion reaction, where the imidazole-containing ligands are replaced with triphenylene-containing ligands with high electron delocalization performance, thus constructing a conductive framework. Compared to conventional three-dimensional polyhedral metal-organic framework materials such as ZIF-8, the chlorinated fullerene-based cathode material disclosed in this invention has a framework with superior conductivity.

[0036] 2. Construction of conductive channels. In this invention, fullerene chloride is filled into the channels of a metal-organic framework material. Upon heating, the fullerene chloride decomposes into fullerene derivatives and chlorine gas, wherein the fullerene derivatives are conductive. Compared with conventional three-dimensional polyhedral metal-organic framework materials such as ZIF-8, the fullerene chloride-based cathode material disclosed in this invention has channels with superior conductivity.

[0037] 3. Spatial confinement of chlorine gas, a charging product. In this invention, the chlorinated fullerene filled in the channels decomposes into chlorine gas upon heating. The chlorine gas is generated in situ within the channels of the metal-organic framework material, and the structural characteristics of the channels spatially confine the chlorine gas. Compared to conventional three-dimensional polyhedral metal-organic framework materials such as ZIF-8, the chlorine gas in the chlorinated fullerene-based cathode material disclosed in this invention is generated in situ within the pore structure of the metal-organic framework material, exhibiting superior spatial confinement performance for chlorine gas.

[0038] 4. Chemisorption of chloride ions, a discharge product. In this invention, the fullerene chloride filled in the channels decomposes upon heating into fullerene derivatives. These fullerene derivatives are generated in situ within the channels of the metal-organic framework material. The strong electron acceptor properties of the fullerene derivatives lead to the chemisorption of chloride ions, a discharge product. Compared to conventional three-dimensional polyhedral metal-organic framework materials such as ZIF-8, the fullerene derivatives in the chlorinated fullerene-based cathode material disclosed in this invention are not only generated in situ within the pore structure of the metal-organic framework material, but their strong electron acceptor properties also lead to strong chemisorption of chloride ions, resulting in superior chemisorption performance for chloride ions.

[0039] 5. This invention constructs a highly conductive metal-organic framework and channels, and generates fullerene derivatives and chlorine gas in situ within the channels, thereby achieving efficient spatial confinement of chlorine gas and strong chemical adsorption of chloride ions, which significantly improves the conductivity and electrochemical reversibility of the chlorinated fullerene-based cathode material. Attached Figure Description

[0040] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope of protection. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0041] Figure 1 AC is a fullerene-based cathode material. 60 Scanning electron microscope images of the surface morphology.

[0042] Figure 2 AC is a fullerene-based cathode material. 60 Photograph of the surface carbon element distribution.

[0043] Figure 3 AC is a fullerene-based cathode material. 60 Photograph of the surface chlorine distribution.

[0044] Figure 4 AC is a fullerene-based cathode material. 60 X-ray photoelectron spectrum of chlorine.

[0045] Figure 5 AC is a fullerene-based cathode material. 60 The Raman spectrum.

[0046] Figure 6 AC is a fullerene-based cathode material. 60 Discharge curves for aqueous zinc-chlorine batteries.

[0047] Figure 7 AC is a fullerene-based cathode material. 60 Curves showing the discharge surface capacity and retention rate versus cycle number for aqueous zinc-chlorine batteries.

[0048] Figure 8 To compare the positive electrode -C 60 Discharge curves for aqueous zinc-chlorine batteries.

[0049] Figure 9 To compare the positive electrode -C 60 Curves showing the discharge surface capacity and retention rate versus cycle number for aqueous zinc-chlorine batteries.

[0050] Figure 10 AC is a fullerene-based cathode material. 70 Discharge curves for aqueous zinc-chlorine batteries.

[0051] Figure 11 AC is a fullerene-based cathode material. 70Curves showing the discharge surface capacity and retention rate versus cycle number for aqueous zinc-chlorine batteries.

[0052] Figure 12 To compare the positive electrode -C 70 Discharge curves for aqueous zinc-chlorine batteries.

[0053] Figure 13 To compare the positive electrode -C 70 Discharge curves for aqueous zinc-chlorine batteries. Detailed Implementation

[0054] To make the objectives, technical solutions, and advantages of this application clearer, the present invention will be further described below with reference to the accompanying drawings and embodiments. The embodiments of the present invention include, but are not limited to, the following embodiments. All other embodiments obtained by those skilled in the art based on the embodiments in this application without inventive effort are within the scope of protection of this application.

[0055] In this embodiment, the term "and / or" is merely a description of the relationship between related objects, indicating that there can be three relationships. For example, A and / or B can represent three situations: A exists alone, A and B exist simultaneously, and B exists alone.

[0056] The terms "first" and "second," etc., used in the specification and claims of this embodiment are used to distinguish different objects, not to describe a specific order of objects. For example, "first target object" and "second target object," etc., are used to distinguish different target objects, not to describe a specific order of target objects.

[0057] In the embodiments of this application, the terms "exemplary" or "for example" are used to indicate that something is an example, illustration, or description. Any embodiment or design that is described as "exemplary" or "for example" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or design. Specifically, the use of the terms "exemplary" or "for example" is intended to present the relevant concepts in a specific manner.

[0058] The technical solution of the present invention will be further described clearly and completely below with reference to the embodiments and accompanying drawings.

[0059] Example 1

[0060] In this embodiment, C 60 Cl6 passes through C 60The synthesis of the fullerene-based cathode material via liquid-phase reaction with ICl is described below, referring to the journal article published by the patent applicant (Cell Reports Physical Science 2021, 2 (12). DOI: 10.1016 / j.xcrp.2021.100646):

[0061] Step 1: Dissolve 0.04 mol of 2-methylimidazole in 80 mL of methanol to form a 2-methylimidazole solution; then add 0.005 mol of fullerene chloride C 60 Cl6 was dissolved in 300 mL of toluene to form a fullerene chloride solution; finally, the fullerene chloride solution was added to a 2-methylimidazole solution to form a mixed solution of fullerene chloride / 2-methylimidazole, and the mixture was stirred continuously for 6 h.

[0062] Step 2: Dissolve 0.005 mol of zinc acetylacetonate in 120 mL of methanol to form a zinc acetylacetonate solution.

[0063] Step 3: Slowly inject the zinc acetylacetone solution into the fullerene / 2-methylimidazole mixed solution to form the precursor reaction solution, and continue stirring for 24 h.

[0064] Step 4: Separate the solid and liquid phases in the reaction solution by centrifugation, wherein the solid phase is a metal-organic precursor.

[0065] Step 5: Wash the metal-organic precursor with methanol to remove unreacted 2-methylimidazolium organic ligands, dry the metal-organic precursor under vacuum at 95°C for 72 h, and disperse 5 mg of the precursor in 1 mL of ultrapure water to form a metal-organic precursor suspension.

[0066] Step 6: Dissolve 10 mg of 2,3,6,7,10,11-hexahydroxytrimethylene in 5 mL of methanol, and rapidly inject the 2,3,6,7,10,11-hexahydroxytrimethylene solution into the precursor dispersion in Step 5 to form a metal-organic precursor / hexahydroxytrimethylene mixed solution.

[0067] Step 7: After stirring, let stand for 24 hours, and then separate the solid phase crystals and liquid phase substances in the metal-organic precursor / hexahydroxytriphenylene mixed solution from Step 6 by centrifugation.

[0068] Step 8: The solid crystals were washed with water and acetone to remove unreacted 2,3,6,7,10,11-hexahydroxytriphenylene organic ligands. The washed solid crystals were then heated at 150°C for 48 h to obtain the fullerene chloride-based cathode material (labeled AC). 60 ).

[0069] like Figure 1 As shown, the AC fullerene-based cathode material 60 It possesses a three-dimensional porous structure formed by the aggregation of two-dimensional nanosheets, and the two-dimensional nanosheet structure is conducive to in-plane electron transport. For example... Figure 2 and Figure 3 As shown, chlorine and carbon elements are uniformly dispersed in two-dimensional nanosheets. Figure 4 As shown, chlorine exists in the form of Cl-Cl bonds and Cl-C bonds in the fullerene-based cathode material AC. 60 In the presence of most chlorine elements as Cl-Cl bonds, it indicates that fullerene chloride (C0) exists as a C0 bond. 60 When Cl6 is heated, most of the chlorine is converted to Cl2; the small amount of chlorine exists as Cl-C bonds, indicating that a small portion of the chlorine reacts with carbon to form chemical bonds. For example... Figure 5 As shown, the AC fullerene-based cathode material 60 Raman spectra of fullerene C 60 The main peak positions are consistent, indicating that fullerene C chloride 60 When Cl6 is heated, most of its carbon elements are converted into fullerene derivatives.

[0070] In this embodiment, the battery performance of the fullerene-based cathode material was tested as follows:

[0071] (1) The fullerene chloride-based cathode material AC 60 Activated carbon (AC) and polytetrafluoroethylene (PTFE) were mixed in ethanol solvent at a mass ratio of 9:0.5:0.5. First, the chlorinated fullerene-based cathode material and activated carbon were ground together. Then, ethanol was added to the mixture of cathode material and activated carbon, and the mixture was stirred to form a slurry. A PTFE emulsion was added to the slurry of cathode material and activated carbon, and the mixture was stirred to disperse it. As ethanol continued to evaporate during stirring, the slurry gradually formed a semi-dry agglomerate. Stirring continued until no solid matter remained on the sidewall of the glass container. Subsequently, a self-supporting membrane of a certain thickness was prepared using a roller pressing process (roller gap 500 μm). This self-supporting membrane was wrapped with filter paper, pressed using a clamp, and dried in an oven for 24 hours (60℃) until the solvent was completely evaporated, yielding the cathode film. The prepared cathode film was cut into 10 mm diameter discs. The cathode material loading in the dried cathode film was approximately 35–45 mg / cm³. 2 AC based on fullerene chloride cathode material 60 The prepared positive electrode film is labeled BC. 60 .

[0072] (2) Battery performance was tested using a Swagelok-type battery. A 1M zinc sulfate aqueous solution was used as the electrolyte, a zinc metal sheet as the negative electrode, and a chlorine-containing positive electrode film BC. 60As the positive electrode. Based on the chlorine-containing positive electrode thin film BC... 60 The assembled zinc-chlorine battery is marked CC. 60 .

[0073] (3) The constant current method is used to test the battery's capacity performance and cycle stability. The charging cutoff voltage is 2.3 V, the discharging cutoff voltage is 1.4 V, and the surface current density of constant current charging and discharging is 2.5 mA / cm². 2 .

[0074] like Figure 6 As shown, AC based on fullerene chloride-based cathode material 60 Zinc-chlorine batteries CC 60 During cyclic charge-discharge, the discharge plateau ranges from approximately 1.9 V to 2.1 V, with the higher discharge voltage related to the Cl2 / Cl ratio. - The high redox potentials are consistent. For example, Figure 7 As shown, AC based on fullerene chloride-based cathode material 60 During the cyclic charge-discharge process, based on the discharge capacity of the first cycle, the discharge capacity retention rates of the zinc-chlorine battery in the 50, 100, 200, 500, 1000, 2000, and 3000 cycles are 99.75%, 99.49%, 96.94%, 94.15%, 92.11%, 88.55%, and 86.77%, respectively.

[0075] To fully demonstrate the effectiveness of the technology disclosed in this patent, the preparation of comparative cathode materials and battery performance tests were conducted as follows:

[0076] (1) Chlorinated fullerene C 60 Cl6, activated carbon (AC), and polytetrafluoroethylene (PTFE) are mixed in ethanol solvent at a mass ratio of 1:8:1. First, fullerene C chloride... 60 Cl6 is ground with activated carbon, and then ethanol is added to the mixture of positive electrode material and activated carbon, stirring until a slurry is formed. The PTFE emulsion is then added to the fullerene C chloride. 60 The slurry of Cl6 and activated carbon was stirred and dispersed. As ethanol continued to evaporate during stirring, the slurry gradually formed a semi-dry agglomerate. Stirring continued until no solid matter remained on the sidewall of the glass container. Subsequently, a self-supporting membrane of a certain thickness was prepared using a roller pressing process (roller gap 500 μm). This self-supporting membrane was wrapped with filter paper, pressed using a clamp, and dried in an oven for 24 hours (60℃) until the solvent was completely evaporated, yielding the positive electrode film. The prepared positive electrode film was cut into 10 mm diameter discs, and the fullerene C chloride in the positive electrode film was dried. 60 The loading capacity of Cl6 is approximately 3–5 mg / cm³. 2Before assembling the battery, the cut positive electrode film was heated at 150°C for 48 h. The positive electrode film prepared based on the comparative positive electrode material was labeled "Comparative Positive Electrode-C". 60 ".

[0077] (2) Battery performance was tested using a Swagelok-type battery. A 1M zinc sulfate aqueous solution was used as the electrolyte, and a zinc metal sheet was used as the negative electrode. The positive electrode was compared to a C-type battery. 60 "As the positive electrode. Based on the contrast positive electrode -C..." 60 The assembled zinc-chlorine battery is marked as "Comparison Battery-C". 60 ".

[0078] (3) The constant current method is used to test the battery's capacity performance and cycle stability. The charging cutoff voltage is 2.3 V, the discharging cutoff voltage is 1.4 V, and the surface current density of constant current charging and discharging is 0.5 mA / cm². 2 .

[0079] like Figure 8 As shown, based on the contrast positive electrode -C 60 Zinc-chlorine batteries "comparison batteries-C" 60 "During the discharge process, the discharge plateau is approximately 1.9 V to 2.1 V, with the higher discharge voltage related to the Cl2 / Cl ratio." - The high redox potentials are consistent. For example, Figure 9 As shown, based on the contrast positive electrode -C 60 Zinc-chlorine batteries "comparison batteries-C" 60 "During the cyclic charge-discharge process, based on the discharge capacity of the first cycle, the discharge capacity retention rates in the 5th, 10th, 25th, and 50th cycles were 97.74%, 92.27%, 83.38%, and 71.27%, respectively."

[0080] To improve the cycle stability of aqueous zinc-chlorine batteries, AC chloride fullerene-based cathode material was used. 60 Compared with the positive electrode -C 60 A comparison reveals that AC based on chlorinated fullerene-based cathode materials... 60 The aqueous zinc-chlorine battery retained 86.77% of its discharge capacity after 3000 cycles, based on the comparison with the cathode-C. 60 The aqueous zinc-chlorine battery retained 71.27% of its discharge capacity after 50 cycles. During the cyclic charge-discharge process of the aqueous zinc-chlorine battery, the discharge capacity retention mainly depends on the content and electrochemical activity of the active material in the positive electrode. This indicates that the AC fullerene-based positive electrode material... 60 Compared to the positive electrode -C 60 It exhibits better fixation performance of positive electrode active materials. On the one hand, this is due to the fact that the AC fullerene-based positive electrode material has better fixation performance. 60The medium- to nano-pore structure provides a stronger spatial confinement for chlorine gas compared to the micron-sized pores in activated carbon; on the other hand, this aligns with the AC chlorinated fullerene-based cathode material. 60 The in-situ generation of fullerene carbon cages and chlorine-based active materials in nanopores is consistent with the stronger chemical adsorption of chloride ions, a discharge product, compared to mechanical blending in activated carbon.

[0081] Example 2

[0082] In this embodiment, C 70 Cl 28 Through C 70 The synthesis of the fullerene-based cathode material via liquid-phase reaction with ICl is described below, referring to the journal article published by the patent applicant (Cell Reports Physical Science 2021, 2 (12). DOI: 10.1016 / j.xcrp.2021.100646):

[0083] Step 1: Dissolve 0.04 mol of 2-methylimidazole in 80 mL of methanol to form a 2-methylimidazole solution; then add 0.005 mol of fullerene chloride C 70 Cl 28 Dissolve in 300 mL toluene to form a fullerene chloride solution; finally, add the fullerene chloride solution to the 2-methylimidazole solution to form a mixed solution of fullerene chloride / 2-methylimidazole, and continue stirring for 6 h;

[0084] Step 2: Dissolve 0.005 mol of zinc acetylacetonate in 120 mL of methanol to form a zinc acetylacetonate solution.

[0085] Step 3: Slowly inject the zinc acetylacetone solution into the fullerene / 2-methylimidazole mixed solution to form the precursor reaction solution, and continue stirring for 24 h.

[0086] Step 4: Separate the solid and liquid phases in the reaction solution by centrifugation, wherein the solid phase is a metal-organic precursor.

[0087] Step 5: Wash the metal-organic precursor with methanol to remove unreacted 2-methylimidazolium organic ligands, dry the metal-organic precursor under vacuum at 60°C for 72 h, and disperse 5 mg of the precursor in 1 mL of ultrapure water to form a metal-organic precursor suspension.

[0088] Step 6: Dissolve 10 mg of 2,3,6,7,10,11-hexahydroxytrimethylene in 5 mL of methanol, and rapidly inject the 2,3,6,7,10,11-hexahydroxytrimethylene solution into the precursor dispersion in Step 5 to form a metal-organic precursor / hexahydroxytrimethylene mixed solution.

[0089] Step 7: After stirring, let stand for 24 hours, and then separate the solid phase crystals and liquid phase substances in the metal-organic precursor / hexahydroxytriphenylene mixed solution from Step 6 by centrifugation.

[0090] Step 8: The solid crystals were washed with water and acetone to remove unreacted 2,3,6,7,10,11-hexahydroxytriphenylene organic ligands. The washed solid crystals were then heated at 150°C for 48 h to obtain the fullerene chloride-based cathode material (labeled AC). 70 ).

[0091] In this embodiment, the battery performance of the fullerene-based cathode material was tested as follows:

[0092] (1) The fullerene chloride-based cathode material AC 70 Activated carbon (AC) and polytetrafluoroethylene (PTFE) were mixed in ethanol solvent at a mass ratio of 9:0.5:0.5. First, the chlorinated fullerene-based cathode material and activated carbon were ground together. Then, ethanol was added to the mixture of cathode material and activated carbon, and the mixture was stirred to form a slurry. A PTFE emulsion was added to the slurry of cathode material and activated carbon, and the mixture was stirred to disperse it. As ethanol continued to evaporate during stirring, the slurry gradually formed a semi-dry agglomerate. Stirring continued until no solid matter remained on the sidewall of the glass container. Subsequently, a self-supporting membrane of a certain thickness was prepared using a roller pressing process (roller gap 500 μm). This self-supporting membrane was wrapped with filter paper, pressed using a clamp, and dried in an oven for 24 hours (60℃) until the solvent was completely evaporated, yielding the cathode film. The prepared cathode film was cut into 10 mm diameter discs. The cathode material loading in the dried cathode film was approximately 35–45 mg / cm³. 2 AC based on fullerene chloride cathode material 70 The prepared positive electrode film is labeled BC. 70 .

[0093] (2) Battery performance was tested using a Swagelok-type battery. A 1M zinc sulfate aqueous solution was used as the electrolyte, a zinc metal sheet as the negative electrode, and a chlorine-containing positive electrode film BC. 70 As the positive electrode. Based on the chlorine-containing positive electrode thin film BC... 70 The assembled zinc-chlorine battery is marked CC. 70 .

[0094] (3) The constant current method is used to test the battery's capacity performance and cycle stability. The charging cutoff voltage is 2.3 V, the discharging cutoff voltage is 1.4 V, and the surface current density of constant current charging and discharging is 2.5 mA / cm². 2 .

[0095] like Figure 10 As shown, AC based on fullerene chloride-based cathode material 70 Zinc-chlorine batteries CC 70 During charging and discharging, the discharge plateau ranges from 1.9 V to 2.1 V, with the higher discharge voltage related to the Cl2 / Cl ratio. - The high redox potentials are consistent. For example, Figure 11 As shown, AC based on fullerene chloride-based cathode material 70 Zinc-chlorine batteries CC 70 During the cyclic charge-discharge process, based on the discharge capacity of the first cycle, the discharge capacity retention rates in the 50, 100, 200, 500, 1000, 2000, and 3000 cycles were 98.36%, 96.72%, 91.80%, 86.07%, 81.97%, 80.33%, and 72.95%, respectively.

[0096] To fully demonstrate the effectiveness of the technology disclosed in this patent, the preparation of comparative cathode materials and battery performance tests were conducted as follows:

[0097] (1) Chlorinated fullerene C 70 Cl 28 Activated carbon (AC) and polytetrafluoroethylene (PTFE) are mixed in ethanol solvent at a mass ratio of 1:8:1. First, fullerene C chloride is added... 70 Cl 28 Grind with activated carbon, then add ethanol to the mixture of positive electrode material and activated carbon, stirring until a slurry is formed. Add the PTFE emulsion to fullerene C chloride. 70 Cl 28 The slurry was stirred and dispersed with activated carbon. As ethanol continued to evaporate during stirring, the slurry gradually formed a semi-dry agglomerate. Stirring continued until no solid matter remained on the sidewalls of the glass container. Subsequently, a self-supporting membrane of a certain thickness was prepared using a roller pressing process (roller gap 300 μm). This self-supporting membrane was wrapped with filter paper, pressed using a clamp, and placed in an oven to dry for 24 hours (60℃) until the solvent was completely evaporated, yielding the positive electrode film. The prepared positive electrode film was cut into 10 mm diameter discs, and the fullerene C chloride in the positive electrode film was dried. 70 Cl 28 The carrying capacity is approximately 3~5 mg / cm³ 2Before assembling the battery, the cut positive electrode film was heated at 150°C for 48 h. The positive electrode film prepared based on the comparative positive electrode material was labeled "Comparative Positive Electrode-C". 70 ".

[0098] (2) Battery performance was tested using a Swagelok-type battery. A 1M zinc sulfate aqueous solution was used as the electrolyte, and a zinc metal sheet was used as the negative electrode. The positive electrode was compared to a C-type battery. 70 "As the positive electrode. The zinc-chlorine battery assembled based on the contrast positive electrode-C70 is labeled as "contrast battery-C". 70 ".

[0099] (3) The constant current method is used to test the battery's capacity performance and cycle stability. The charging cutoff voltage is 2.3 V, the discharging cutoff voltage is 1.4 V, and the surface current density of constant current charging and discharging is 0.5 mA / cm². 2 .

[0100] like Figure 12 As shown, based on the contrast positive electrode -C 70 During discharge, the zinc-chlorine battery exhibits a discharge plateau of approximately 1.9 V to 2.1 V. The higher discharge voltage is related to the Cl₂ / Cl₂ ratio. - The high redox potentials are consistent. For example, Figure 13 As shown, based on the contrast positive electrode -C 70 During the cyclic charge-discharge process, the discharge capacity retention rates of the zinc-chlorine battery in the 5th, 10th, and 25th cycles, based on the discharge capacity of the first cycle, were 90.05%, 72.36%, and 59.58%, respectively.

[0101] To improve the cycle stability of aqueous zinc-chlorine batteries, AC chloride fullerene-based cathode material was used. 70 Compared with the positive electrode -C 70 A comparison reveals that AC based on chlorinated fullerene-based cathode materials... 70 The aqueous zinc-chlorine battery retained 72.59% of its discharge capacity after 3000 cycles, based on a comparison with the cathode-C. 60 The aqueous zinc-chlorine battery retained 59.58% of its discharge capacity after 25 cycles. During the cyclic charge-discharge process of the aqueous zinc-chlorine battery, the discharge capacity retention mainly depends on the content and electrochemical activity of the active material in the positive electrode. This indicates that the AC fullerene-based positive electrode material... 70 Compared to the positive electrode -C 70 It exhibits better fixation performance of positive electrode active materials. On the one hand, this is due to the fact that the AC fullerene-based positive electrode material has better fixation performance. 70 The nanopores in organometallic framework materials provide stronger spatial confinement for the charging product chlorine gas compared to the micropores in activated carbon; on the other hand, this is consistent with the AC fullerene-based cathode material. 70The in-situ generation of fullerene carbon cages and chlorine-based active materials in nanopores is consistent with the stronger chemical adsorption of chloride ions, a discharge product, compared to mechanical blending in activated carbon.

[0102] Chen et al. reported a zinc-chlorine battery system assembled using manganese dioxide-modified carbon felt as the positive electrode, 1M zinc sulfate and 1M lithium chloride aqueous solution as the electrolyte, and metallic zinc sheet as the negative electrode. The system required approximately 100 activation cycles to reach peak performance (Small Methods 2024, 8 (6), 2201553. DOI: 10.1002 / smtd.202201553.). In contrast, the zinc-chlorine battery based on fullerene-based cathode material disclosed in this invention does not require a significant activation process. This is because the cathode active material is introduced during the cathode preparation process in this invention, rather than being generated through later conversion as reported in the literature, which improves the battery's usability.

[0103] Wang et al. reported on improving the performance of zinc-bromine flow batteries by utilizing the pore size characteristics of cage-like porous carbon (Advanced Materials 2017, 29 (22), 1605815. DOI: 10.1002 / adma.201605815.); Fan et al. reported on improving the performance of supercapacitors by utilizing the pore size characteristics of multi-walled carbon nanotubes (Angewandte Chemie International Edition 2023, 62 (2), e202215342. DOI: 10.1002 / anie.202215342.). Compared to these reports, firstly, the chlorine-based active material disclosed in this invention is present in the positive electrode, rather than in the electrolyte as reported in the literature. This improves the utilization rate of chlorine confined in the pores of the porous positive electrode material, especially in the deep pores. Secondly, the chlorinated fullerene-based positive electrode material disclosed in this invention employs a dual-fixed positive electrode design (the pore structure of the metal-organic framework material spatially confines the generated chlorine gas, and the interaction between the fullerene derivative and chloride ions effectively inhibits the migration and loss of chloride ions), rather than the single pore confinement effect reported in the literature. This improves the utilization rate of the chlorine-based active material in the porous positive electrode material and contributes to the improvement of battery cycle performance. Based on the above analysis, it is clear that the chlorinated fullerene-based positive electrode material disclosed in this patent differs significantly from the porous positive electrode materials reported in the literature, particularly in its design for the chemical adsorption of chloride ions, a discharge product.

[0104] In summary, this invention achieves synergistic regulation of active material confinement and conductivity enhancement in cathode materials by introducing fullerene chloride during the synthesis of metal-organic precursors and further preparing fullerene derivatives and chlorine gas-filled cathode materials through ligand conversion. On one hand, the in-situ generation of fullerene derivatives and chlorine gas within the pores enables strong chemisorption of chloride ions and efficient spatial confinement of chlorine gas. On the other hand, the high electron delocalization performance of triphenylene ligands is utilized to construct the conductive framework, and conductive fullerene derivatives are used to construct conductive channels. Overall, the technology disclosed in this invention effectively improves the conductivity, structural stability, and electrochemical reaction reversibility of cathode materials, thereby significantly improving the electrochemical performance of aqueous zinc-chlorine batteries and demonstrating promising application prospects.

[0105] The above embodiments are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any changes made based on the design principles of the present invention, or any non-creative modifications made thereon, shall fall within the scope of protection of the present invention.

Claims

1. A fullerene-based cathode material, characterized in that, The cathode material includes a metal-organic framework material and chlorine gas and fullerene derivatives filling its pores; The metal-organic framework material is generated by reacting a metal-organic precursor with a triphenylene-containing ligand, wherein the triphenylene-containing ligand includes hexahydroxytriphenylene; the metal-organic precursor is generated by reacting an imidazole-containing ligand, a fullerene chloride, and a metal ion, wherein the imidazole-containing ligand includes 2-methylimidazole, and the metal ion includes zinc ions. The pore structure of the metal-organic framework material spatially confines the charging product chlorine gas, and the electron acceptor properties of the fullerene derivative chemically adsorb the discharge product chloride ions, thereby achieving dual fixation of the charging and discharging products. The molecular formula of the fullerene derivative is Cx, where x is 60, 70, 76, 78 or 84. The framework of the metal-organic framework material contains triphenylene ligands with high electron delocalization performance, and the channels of the metal-organic framework material are filled with conductive fullerene derivatives, thereby achieving a dual improvement in the conductivity of the cathode material.

2. The fullerene-based cathode material according to claim 1, characterized in that, The molecular formula of the fullerene chloride is: C x Cl y x is 60, 70, 76, 78 or 84, and the ratio of y to x is 0.1 to 0.

5.

3. A method for preparing a fullerene-based cathode material according to any one of claims 1 to 2, characterized in that, Includes the following steps: Step 1: Dissolve fullerene chloride uniformly in toluene to form a fullerene chloride solution; 2-Methylimidazole was uniformly dissolved in methanol to form a 2-methylimidazole solution; a fullerene chloride solution was added to the 2-methylimidazole solution to form a fullerene chloride / 2-methylimidazole mixed solution; Step 2: Dissolve zinc acetylacetonate in methanol to form a zinc acetylacetonate solution; Step 3: Add the fullerene chloride / 2-methylimidazole mixed solution from Step 1 to the zinc acetylacetone solution from Step 2 to form a precursor reaction solution; Step 4: After the set reaction time, the solid-phase precipitate product and the liquid-phase solution in the precursor reaction solution are separated. The obtained solid-phase precipitate product is a metal-organic precursor. Step 5: Wash and dry the metal-organic precursor with methanol, and then disperse the metal-organic precursor in water to form a metal-organic precursor dispersion. Step 6: Dissolve hexahydroxytriphenylene in ethanol to form a hexahydroxytriphenylene solution, and then add the hexahydroxytriphenylene solution to the metal-organic precursor dispersion to form a metal-organic precursor / hexahydroxytriphenylene mixed solution; Step 7: After the set reaction time, separate the solid crystals and reaction solution in the metal-organic precursor / hexahydroxytriphenylene mixed solution from Step 6; Step 8: Wash the solid crystals with water and acetone, and then heat the solid crystals at a set temperature and time to obtain the fullerene-based cathode material.

4. The method for preparing the fullerene-based cathode material according to claim 3, characterized in that, In step one, the concentration of fullerene chloride in the mixed solution is 0.001~1 mol / L, the concentration of 2-methylimidazole in the mixed solution is 0.001~1 mol / L, and the molar ratio of fullerene chloride to 2-methylimidazole in the mixed solution is 1:1~1:

10.

5. The method for preparing the fullerene-based cathode material according to claim 4, characterized in that, In step two, the concentration of the zinc acetylacetone solution is 0.01~10 mol / L.

6. The method for preparing the fullerene-based cathode material according to claim 5, characterized in that, The reaction time set in step two is 2 to 128 hours, and the reaction time set in step seven is 2 to 128 hours.

7. The method for preparing the fullerene-based cathode material according to claim 6, characterized in that, In step three, the molar ratio of zinc acetylacetonate to 2-methylimidazole in the precursor reaction solution is 1:5 to 1:

60.

8. The method for preparing the fullerene-based cathode material according to claim 7, characterized in that, In step five, the mass concentration of the metal-organic precursor dispersion is 2-50 mg / mL, and / or, in step six, the mass concentration of the hexahydroxytriphenylene solution is 2-50 mg / mL, and the mass ratio of the metal-organic precursor to hexahydroxytriphenylene in the metal-organic precursor / hexahydroxytriphenylene mixed solution is 1:1 to 1:

5.

9. The method for preparing the fullerene-based cathode material according to claim 8, characterized in that, In step eight, the temperature is set to 100~150℃ and the time is set to 12~120 h.

10. An aqueous zinc-chlorine battery based on a fullerene-based cathode material, comprising a cathode, a cathode, an electrolyte, and a separator, characterized in that, The cathode is the fullerene-based cathode material according to any one of claims 1 to 9.

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