Solid-phase synthesis method for large-scale preparation of two-dimensional polyphthalocyanine framework and application of solid-phase synthesis method
Two-dimensional polyphthalocyanine frameworks were prepared by solid-phase synthesis using 1,2,4,5-benzenetetracarbononitrile as raw material, which was ground and mixed with metal salts and heated under vacuum or inert atmosphere. This solved the problem of large-scale synthesis of highly crystalline materials in existing technologies, realized efficient and environmentally friendly industrial-grade production, and showed excellent catalytic performance in lithium-sulfur batteries.
Patent Information
- Application Number
- CN202511473273.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-10-15
- Publication Date
- 2025-12-16
AI Technical Summary
Existing technologies are insufficient for the large-scale and efficient synthesis of highly crystalline two-dimensional polyphthalocyanine framework materials. Conventional methods suffer from problems such as high equipment requirements, excessive use of organic solvents, and severe environmental pollution.
A solid-phase synthesis method was adopted, using 1,2,4,5-benzenetetracarbonitrile as raw material, which was ground and mixed with metal salt and then subjected to polymerization reaction under vacuum or inert atmosphere. Two-dimensional polyphthalocyanine frameworks were prepared. The synthesis environment was vacuum or inert atmosphere, the temperature was 210~400 ℃, and the time was 6~144 hours. The crude product was washed and purified to obtain a dark green solid powder.
A green, environmentally friendly, low-cost, and high-yield large-scale preparation of highly crystalline two-dimensional polyphthalocyanine framework materials has been achieved, which is suitable for industrial-scale synthesis. The materials can efficiently catalyze the conversion of lithium polysulfides in liquid lithium-sulfur batteries, exhibiting excellent electrochemical catalytic performance.
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Abstract
Description
Technical Field
[0001] This invention relates to organic polymer material synthesis technology, and in particular to a solid-phase synthesis method for large-scale preparation of two-dimensional polyphthalocyanine frameworks and its application. Background Technology
[0002] Two-dimensional polyphthalocyanine frameworks (PPBs) are a class of periodic porous crystalline materials formed by phthalocyanine molecules linked by covalent bonds. They possess characteristics such as high specific surface area and interconnected, regularly ordered sub-nanometer-scale pores (pore size ~0.7 nm), making them widely used in electrocatalysis, gas separation, and other fields. Currently, the large-scale, efficient synthesis of highly crystalline PPBs remains challenging because most reported methods often yield only amorphous or microcrystalline products. This is primarily due to the low yield and irreversibility of the tetramerization reaction of cyano groups. For organic porous framework materials, improving crystallinity is beneficial for enhancing the conductivity and specific surface area of PPBs.
[0003] Currently, there are three main methods for synthesizing phthalocyanine molecules: 1) Microwave method, which uses a microwave reactor to carry out a tetramerization reaction. (Thesis) ACS Nano. The method used in (2019, 13, 878-884) has high equipment requirements and uses a large amount of organically toxic solvents, which does not meet the requirements for large-scale preparation and the development of green chemistry. 2) Ionothermal method, patent CN117659394A and paper ( J. Am. Chem. Soc. 2025, 147, 21089-21096; Angew. Chem. Int. Ed. 2023, 62 Reactions requiring temperatures above 400℃ (e202309775) will result in severe carbonization of the product, low yield, and require large amounts of hydrochloric acid for post-processing to remove metals or metal salts, potentially causing environmental pollution. 3) Solvothermal method, which uses metal salts or organic bases as catalysts for conventional chemical synthesis. (Thesis) Sci. China Chem. 2024, 67 , 2092-2101; Natl. Sci. Rev. 2025, 12 44) This method was used, but it employs high-boiling-point organic solvents, generating a large amount of organic waste liquid, and the experiment is difficult to scale up. None of the above methods are suitable for the large-scale preparation of crystalline two-dimensional polyphthalocyanine framework materials.
[0004] It should be noted that the information disclosed in the background section above is only for understanding the background of this application, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention
[0005] The main purpose of the present application is to overcome the defects in the background art, provide a solid phase synthesis method for large-scale preparation of two-dimensional polyphthalocyanine framework and application thereof.
[0006] To achieve the above-mentioned purpose, the present application adopts the following technical solutions: A solid phase synthesis method for large-scale preparation of two-dimensional polyphthalocyanine framework, comprising the following steps: 1,2,4,5-benzene tetracarbonitrile is used as raw material, mixed with metal salt after grinding, and then sealed heating under vacuum or inert atmosphere to carry out solid phase polymerization reaction to prepare two-dimensional polyphthalocyanine framework. The metal salt is selected from one or more of alkali metal salt and transition metal salt.
[0007] Further, the cation of the alkali metal salt includes lithium, sodium, potassium and the like; and the anion includes fluoride, chloride, bromide, iodide, thiocyanate, bis-trifluoromethanesulfonylimide and the like. The cation of the transition metal salt includes iron, cobalt, nickel, copper, zinc and the like; and the anion includes chloride, bromide, iodide, thiocyanate and the like.
[0008] Further, in the solid phase polymerization reaction, the total mass ratio of 1,2,4,5-benzene tetracarbonitrile to metal salt is 1:2 to 1:100.
[0009] Further, in the solid phase polymerization reaction, the synthesis environment is vacuum or inert gas atmosphere, the reaction temperature is 210-400 DEG C, and the reaction time is 6-144 hours.
[0010] Further, 1,2,4,5-benzene tetracarbonitrile and metal salt are fully ground and mixed to carry out solid phase thermal polymerization reaction; the crude product is washed and purified with deionized water and ethanol for several times and then dried to obtain two-dimensional polyphthalocyanine framework containing alkali metal or transition metal, which has the property of dark green solid powder.
[0011] The application of the two-dimensional polyphthalocyanine framework uses the two-dimensional polyphthalocyanine framework as a sulfur reduction catalyst to catalyze the conversion of lithium polysulfide in a liquid lithium-sulfur battery.
[0012] The present application has the following beneficial effects: The present application provides a solid phase synthesis method for large-scale preparation of two-dimensional polyphthalocyanine framework and application thereof (especially electrochemical catalytic application in lithium-sulfur battery), and the synthesis method of the present application is a simple operation, green, fast, large batch, low cost and efficient synthesis method for preparing high crystalline two-dimensional polyphthalocyanine framework material.
[0013] The synthesis of the two-dimensional polyphthalocyanine framework is carried out by taking 1,2,4,5-benzene tetracarbonitrile as raw material, mixing with alkali metal salt, transition metal salt and their composite salt after grinding, and then sealing and heating at 400 DEG C or below to carry out solid phase polymerization reaction. The synthesis method has the advantages of simple operation, green environmental protection and easy scale production, and can prepare a series of two-dimensional polyphthalocyanine framework materials containing alkali metal or transition metal with high yield. In the application, the two-dimensional polyphthalocyanine cobalt is used as a positive electrode catalyst of a liquid lithium-sulfur battery, and the experimental results show that the two-dimensional polyphthalocyanine cobalt has excellent electrochemical catalytic performance. At a current density of 1C (1C=1675mA / g), the battery still retains a discharge specific capacity of 700mAh / g after 400 cycles.
[0014] The synthesis method has universality, and can synthesize two-dimensional polyphthalocyanine framework materials with high crystallinity, high thermal stability and catalytic activity with high yield. The method can be extended to synthesize two-dimensional polyphthalocyanine framework materials containing double metals or even multiple metals, and the metal types are not limited to transition metals such as iron, cobalt, nickel, copper and zinc, or even all metals in the periodic table that can be coordinated with phthalocyanine, and can be applied to not only the oxidation-reduction reaction of lithium polysulfide in the liquid lithium-sulfur battery.
[0015] In general, the present application provides a solid phase synthesis method for preparing two-dimensional polyphthalocyanine framework materials with high crystallinity, which is green, low cost, scalable and high yield. In view of the problems existing in the existing phthalocyanine synthesis method, the alkali metal salt template catalytic mechanism is used to efficiently prepare a series of two-dimensional polyphthalocyanine framework materials, and no organic solvent is needed in the preparation process, which is suitable for industrial scale synthesis process.
[0016] Other beneficial effects in the embodiments of the present application will be further described below. BRIEF DESCRIPTION OF DRAWINGS
[0017] Figure 1 It is a schematic diagram of the molecular structure of the two-dimensional polyphthalocyanine framework related to the present application; Figure 2 It is a synthesis route diagram of a plurality of two-dimensional polyphthalocyanine framework related to the present application; Figure 3 It is an X-ray diffraction pattern of two-dimensional polyphthalocyanine potassium in embodiment 1 of the present application; Figure 4 It is an X-ray diffraction pattern of two-dimensional polyphthalocyanine sodium in embodiment 2 of the present application; Figure 5 It is an X-ray diffraction pattern of two-dimensional polyphthalocyanine lithium in embodiment 3 of the present application; Figure 6 It is an X-ray diffraction pattern of two-dimensional polyphthalocyanine cobalt in embodiment 4 of the present application; Figure 7X-ray diffraction pattern of two-dimensional polyphthalocyanine sodium in Example 5 of the present application; Figure 8 X-ray diffraction pattern of two-dimensional polyphthalocyanine nickel in Example 6 of the present application; Figure 9 X-ray diffraction pattern of two-dimensional polyphthalocyanine cobalt in Example 7 of the present application; Figure 10 Infrared spectrum of two-dimensional polyphthalocyanine potassium in Example 1 of the present application; Figures 11A-11C Thermogravimetric curve of two-dimensional polyphthalocyanine potassium, two-dimensional polyphthalocyanine sodium and two-dimensional polyphthalocyanine cobalt in Examples 1, 2 and 7 of the present application, respectively; Figure 12 Cyclic voltammetry test of two-dimensional polyphthalocyanine cobalt in Example 7 of the present application as a catalyst in a liquid lithium-sulfur battery; Figure 13 Long cycle test of two-dimensional polyphthalocyanine cobalt in Example 7 of the present application as a catalyst in a liquid lithium-sulfur battery. DETAILED DESCRIPTION
[0018] The following detailed description of the embodiments of the present application is provided. It should be emphasized that the following description is merely exemplary and is not intended to limit the scope of the present application and its applications.
[0019] In addition, the terms "first", "second", "third", etc. are used only for descriptive purposes and are not to be construed as indicating or implying relative importance or an indicated number of technical features. Thus, features defined with "first", "second" or "third" can explicitly or implicitly include one or more of the features. In the description of the embodiments of the present application, the meaning of "a plurality of" is two or more, unless otherwise specifically limited.
[0020] The present application aims to realize the large-scale green preparation and application expansion of high-crystalline two-dimensional polyphthalocyanine framework materials, and proposes a solid-phase synthesis method of sealing and heating after grinding and mixing 1,2,4,5-benzene tetracarbonitrile and metal salt as raw materials; the method is simple in operation, low in cost and high in yield, and can prepare a series of two-dimensional polyphthalocyanine framework materials containing metal, and the material can efficiently catalyze the conversion of lithium polysulfide in a liquid lithium-sulfur battery.
[0021] The solid-phase synthesis method for large-scale preparation of two-dimensional polyphthalocyanine framework provided by the embodiments of the present application comprises the following steps: 1,2,4,5-benzene tetracarbonitrile is used as raw material, and is ground and mixed with metal salt, and then sealed and heated for solid-phase polymerization reaction to prepare two-dimensional polyphthalocyanine framework under vacuum or inert gas atmosphere; The metal salt is selected from one or more of alkali metal salt and transition metal salt.
[0022] Figure 1A two-dimensional polyphthalocyanine framework synthesized by the synthetic method described in the present application is shown.
[0023] Figure 2 A synthetic route of various two-dimensional polyphthalocyanine frameworks synthesized by the synthetic method described in the present application is shown.
[0024] In some embodiments, the alkali metal salt comprises lithium, sodium, potassium, and the like as the cation, and fluorine, chlorine, bromine, iodine, thiocyanate, bis-trifluoromethanesulfonylimide, and the like as the anion. The transition metal salt comprises iron, cobalt, nickel, copper, zinc, and the like as the cation, and chlorine, bromine, iodine, thiocyanate, and the like as the anion.
[0025] In some embodiments, in the solid-phase polymerization reaction, the total mass ratio of 1,2,4,5-benzene tetracarbonitrile to metal salt is 1:2-1:100. When the metal salt is a composite metal salt, the mass ratio of alkali metal salt to transition metal salt is not limited.
[0026] In some embodiments, in the solid-phase polymerization reaction, the synthesis environment is vacuum or inert gas atmosphere, the reaction temperature is 210-400 ℃, and the reaction time is 6-144 hours.
[0027] In some embodiments, 1,2,4,5-benzene tetracarbonitrile and metal salt are thoroughly ground and mixed, and a solid-phase thermal polymerization reaction is performed under inert gas atmosphere; the crude product is purified by washing with deionized water and ethanol multiple times and then dried to obtain a two-dimensional polyphthalocyanine framework containing alkali metal or transition metal, which has the property of dark green solid powder.
[0028] The embodiments of the present application also provide the application of the two-dimensional polyphthalocyanine framework, which is used as a sulfur reduction catalyst to catalyze the conversion of lithium polysulfide in lithium-sulfur batteries.
[0029] Specifically, a solid-phase synthesis method for large-scale preparation of a two-dimensional polyphthalocyanine framework includes the following processes: 1,2,4,5-benzene tetracarbonitrile and metal salt are ground and mixed according to a certain proportion, then transferred to a Schlenk tube for vacuum sealing, heated at an appropriate temperature for a certain time to obtain a crude product. The obtained crude product is taken out and then washed with deionized water and ethanol in sequence to obtain a pure two-dimensional polyphthalocyanine framework material, which has the property of dark green solid powder.
[0030] The metal salt is selected from one or more of alkali metal salt, transition metal salt, including fluorinated salt, chlorinated salt, brominated salt, iodized salt, thiocyanate salt and bis-trifluoromethanesulfonylimide salt of alkali metal or transition metal salt. The fluorinated salt is specifically sodium fluoride, potassium fluoride, etc.; the chlorinated salt is specifically lithium chloride, sodium chloride, potassium chloride, zinc chloride, etc., the brominated salt is specifically lithium bromide, sodium bromide, potassium bromide, copper bromide, nickel bromide, cobalt bromide, ferrous bromide, etc.; the iodized salt is specifically lithium iodide, sodium iodide, potassium iodide, copper iodide, nickel iodide, cobalt iodide, ferrous iodide, etc.; the thiocyanate salt is specifically potassium thiocyanate, sodium thiocyanate, zinc thiocyanate, cobalt thiocyanate; the bis-trifluoromethanesulfonylimide salt is specifically lithium bis-trifluoromethanesulfonylimide, sodium bis-trifluoromethanesulfonylimide, potassium bis-trifluoromethanesulfonylimide, etc., and a mixture of different proportions of all the above-mentioned salts, and should also include all the above-mentioned salts and transition metal chlorinated salt, brominated salt, iodized salt, acetate salt, sulfate salt, etc.
[0031] In the process, the mass ratio of 1,2,4,5-benzene tetracarbonitrile and salt is 1:2-1:100.
[0032] In the process, the reaction environment is vacuum or inert atmosphere.
[0033] In the process, the reaction temperature is 210-400 DEG C.
[0034] In the process, the reaction time is 6-144 hours.
[0035] In the process, the crude product is sequentially extracted and filtered by deionized water and ethanol to obtain dark green target product, and the reaction yield is 80%-95%.
[0036] In addition, the application provides an application of the two-dimensional polyphthalocyanine framework material, and the two-dimensional polyphthalocyanine cobalt is used as a catalyst to perform electrocatalytic reduction of lithium polysulfide in a liquid lithium-sulfur battery.
[0037] The synthesis method of the application has universality, and can synthesize two-dimensional polyphthalocyanine framework materials with high crystallinity, high thermal stability and catalytic activity at a high yield. The method can be expanded to prepare two-dimensional polyphthalocyanine framework materials containing double metals or even multiple metals, and the metal types are not limited to transition metals such as iron, cobalt, nickel, copper and zinc, or even all metals in the periodic table that can be coordinated with phthalocyanine, and can be applied to not only the redox reaction of lithium polysulfide in a liquid lithium-sulfur battery.
[0038] The specific embodiments and experimental results of the application are further described below.
[0039] Example 1: Synthesis method based on potassium thiocyanate salt: (1) In an argon filled glove box, 1 g of potassium thiocyanate and 0.1 g of 1,2,4,5-benzenetetracarbonitrile were ground together in a mortar to form a solid A; (2) The solid A was transferred to a 50 mL Schlenk tube and sealed; (3) The Schlenk tube was removed from the glove box and placed in a heating mantle at 300 °C for 6 hours; (4) The product was washed with deionized water and ethanol several times and dried in a vacuum oven at 120 °C overnight to obtain a dark green solid powder.
[0040] Example 2: Synthesis method based on sodium thiocyanate salt: (1) In an argon filled glove box, 5 g of sodium thiocyanate and 0.4 g of 1,2,4,5-benzenetetracarbonitrile were ground together in a mortar to form a solid B; (2) The solid B was transferred to a 50 mL Schlenk tube and sealed; (3) The Schlenk tube was removed from the glove box and placed in a heating mantle at 310 °C for 8 hours; (4) The product was washed with deionized water and ethanol several times and dried in a vacuum oven at 120 °C overnight to obtain a dark green solid powder.
[0041] Example 3: Synthesis method based on lithium bis(trifluoromethanesulfonyl)imide salt: (1) In an argon filled glove box, 8 g of lithium bis(trifluoromethanesulfonyl)imide and 0.8 g of 1,2,4,5-benzenetetracarbonitrile were ground together in a mortar to form a solid C; (2) The solid C was transferred to a 50 mL Schlenk tube and sealed; (3) The Schlenk tube was removed from the glove box and placed in a heating mantle at 230 °C for 24 hours; (4) The product was washed with deionized water and ethanol several times and dried in a vacuum oven at 120 °C overnight to obtain a dark green solid powder.
[0042] Example 4: Synthesis method based on cobalt thiocyanate salt: (1) In an argon filled glove box, 2 g of cobalt thiocyanate and 0.1 g of 1,2,4,5-benzenetetracarbonitrile were ground together in a mortar to form a solid D; (2) The solid D was transferred to a 50 mL Schlenk tube and sealed; (3) The Schlenk tube was removed from the glove box and placed in a heating mantle at 210 °C for 18 hours; (4) The product was washed with deionized water, ethanol several times and dried in a vacuum oven at 120 °C overnight to obtain a dark green solid powder.
[0043] Example 5: Synthesis method based on sodium iodide salt: (1) In an argon-filled glove box, 20 g of sodium iodide and 5 g of 1,2,4,5-benzotetra-carbonitrile were mixed uniformly in a mortar to form a solid E; (2) The solid E was transferred to a 250 mL Schlenk tube and sealed; (3) The Schlenk tube was taken out of the glove box and placed in a 330°C heating jacket for heating for 60 hours; (4) The product was washed with deionized water and ethanol for multiple times, and dried in a vacuum drying oven at 120°C overnight to obtain a dark green solid powder.
[0044] Example 6: Synthesis method based on nickel iodide: (1) In an argon-filled glove box, 50 g of nickel iodide and 10 g of 1,2,4,5-benzotetra-carbonitrile were mixed uniformly in a mortar to form a solid G; (2) The solid G was transferred to a 250 mL Schlenk tube and vacuumized, and then sealed; (3) The Schlenk tube was taken out of the glove box and placed in a 290°C heating jacket for heating for 8 hours; (4) The product was washed with deionized water and ethanol for multiple times, and dried in a vacuum drying oven at 120°C overnight to obtain a dark green solid powder.
[0045] Example 7: Synthesis method based on cobalt chloride-sodium iodide composite salt: (1) In an argon-filled glove box, 0.3 g of cobalt chloride and 1 g of sodium iodide were mixed with 0.1 g of 1,2,4,5-benzotetra-carbonitrile in a mortar to form a solid F; (2) The solid F was transferred to a 50 mL Schlenk tube and vacuumized, and then sealed; (3) The Schlenk tube was taken out of the glove box and placed in a 310°C heating jacket for heating for 20 hours; (4) The product was washed with deionized water and ethanol for multiple times, and dried in a vacuum drying oven at 120°C overnight to obtain a dark green solid powder.
[0046] Example 8: The two-dimensional polymeric metal phthalocyanine framework prepared by the method of the application is used for catalytic conversion of lithium polysulfide in a liquid lithium-sulfur battery.
[0047] The two-dimensional polyphthalocyanine cobalt material is mixed with carbon-sulfur composite (carbon-sulfur ratio of 3:7) and conductive agent carbon nanotube and binder polyvinylidene fluoride as a catalyst, and the mass ratio of the four is 1:7:1:1, to prepare a positive electrode sheet. A button cell is assembled in the order of positive electrode shell, positive electrode, separator, negative electrode, gasket, spring and negative electrode shell. The battery performance is tested on an electrochemical workstation and a blue cell test system.
[0048] Figure 3 The X-ray diffraction pattern of the two-dimensional polyphthalocyanine potassium in Example 1 of the application is shown. Figure 4 The X-ray diffraction pattern of the two-dimensional polyphthalocyanine sodium in Example 2 of the application is shown. Figure 5 The X-ray diffraction pattern of the two-dimensional polyphthalocyanine lithium in Example 3 of the application is shown. Figure 6 The X-ray diffraction pattern of the two-dimensional polyphthalocyanine cobalt in Example 4 of the application is shown. Figure 7 The X-ray diffraction pattern of the two-dimensional polyphthalocyanine sodium in Example 5 of the application is shown. Figure 8 The X-ray diffraction pattern of the two-dimensional polyphthalocyanine nickel in Example 6 of the application is shown. Figure 9 The X-ray diffraction pattern of the two-dimensional polyphthalocyanine cobalt in Example 7 of the application is shown. Figure 10 The infrared spectrum of the two-dimensional polyphthalocyanine potassium in Example 1 of the application is shown. Figures 11A-11C The thermogravimetric curve of the two-dimensional polyphthalocyanine potassium, two-dimensional polyphthalocyanine sodium and two-dimensional polyphthalocyanine cobalt in Examples 1, 2 and 7 of the application is shown respectively. Figure 12 The cyclic voltammetry test of the two-dimensional polyphthalocyanine cobalt in Example 7 of the application as a catalyst in a liquid lithium-sulfur battery is shown. Figure 13 The long cycle test of the two-dimensional polyphthalocyanine cobalt in Example 7 of the application as a catalyst in a liquid lithium-sulfur battery is shown. The experimental results show that the two-dimensional polyphthalocyanine framework material synthesized in the application has high crystallinity, high thermal stability and catalytic activity. In particular, the two-dimensional polyphthalocyanine cobalt has the ability to catalyze the conversion of lithium polysulfide, and the lithium-sulfur battery has a discharge specific capacity of 700 mAh g –1 at a current of 1675 mA g –1 after 400 cycles of long cycle test. The two-dimensional polyphthalocyanine cobalt and other two-dimensional polyphthalocyanine framework materials synthesized in the application can be used as catalysts for efficient conversion of lithium polysulfide.
[0049] The above further describes the present application in conjunction with specific / preferred embodiments, and cannot be deemed to limit the specific implementation of the present application to these descriptions. For those skilled in the art to which the present application belongs, without departing from the concept of the present application, they can make several substitutions or variations to the described embodiments, and these substitutions or variations shall be deemed to fall within the protection scope of the present application. In the description of the present application, the description of the terms "an embodiment", "some embodiments", "a preferred embodiment", "an example", "a specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are contained in at least one embodiment or example of the present application. In the present application, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In the case of no mutual contradiction, those skilled in the art can combine and combine the different embodiments or examples described in the present application and the features of the different embodiments or examples. Although the embodiments of the present application and their advantages have been described in detail, it should be understood that various changes, substitutions and modifications can be made herein without departing from the scope of protection of the patent application.
Claims
1. A solid phase synthesis method for the large scale preparation of two-dimensional polyphthalocyanine frameworks, characterized by, The method comprises the following steps: A two-dimensional polyphthalocyanine framework is prepared by solid-phase polymerization reaction of 1,2,4,5-benzene tetracarbonitrile and a metal salt under vacuum or inert atmosphere after grinding and mixing. The metal salt is selected from one or more of alkali metal salts and transition metal salts.
2. The synthesis method according to claim 1, wherein the alkali metal salt comprises lithium, sodium or potassium as cations and fluorine, chlorine, bromine, iodine, thiocyanate or bis-trifluoromethanesulfonylimide as anions. The transition metal salt comprises iron, cobalt, nickel, copper or zinc as cations and chlorine, bromine, iodine or thiocyanate as anions.
3. The synthesis method according to claim 1 or 2, wherein the total mass ratio of 1,2,4,5-benzene tetracarbonitrile to the metal salt in the solid-phase polymerization reaction is 1:2 to 1:
100.
4. The synthesis method according to any one of claims 1 to 3, wherein the synthesis environment in the solid-phase polymerization reaction is vacuum or inert atmosphere, the reaction temperature is 210 to 400 DEG C, and the reaction time is 6 to 144 hours.
5. The synthesis method according to any one of claims 1 to 4, wherein the 1,2,4,5-benzene tetracarbonitrile and the metal salt are sufficiently ground and mixed before the solid-phase thermal polymerization reaction. The crude product is washed with deionized water and ethanol for multiple times, dried, and then a two-dimensional polyphthalocyanine framework containing alkali metal or transition metal is obtained in the form of dark green solid powder.
6. A two-dimensional polyphthalocyanine framework synthesized by the synthesis method according to any one of claims 1 to 5. The two-dimensional polyphthalocyanine framework is used as a sulfur reduction catalyst to catalyze the conversion of lithium polysulfide in a liquid lithium-sulfur battery. 7. Use of a two-dimensional polypyrometallolophorine framework according to claim 6, characterized in that,