A porphyrin compound, its preparation method and application

Abstract

This invention provides a porphyrin compound, its preparation method, and its applications. The porphyrin compound is obtained by first reacting formaldehyde with pyrrole to obtain bipyrrole; then reacting bipyrrole with CHO-R to synthesize a porphyrin ring. This invention introduces phenothiazine or carbazole groups into the porphyrin molecule, providing multiple active sites for the anion, and extending the conjugated structure after the in-situ polymerization process, significantly enhancing the structural stability of the porphyrin molecule. The resulting porphyrin compound exhibits excellent structural stability, high discharge voltage, and excellent rate performance.

Description

Technical Field

[0001] This invention belongs to the field of metal-ion battery technology, specifically relating to a porphyrin compound, its preparation method, and its application in the cathode material of metal-ion batteries. Background Technology

[0002] Addressing climate change and energy demand fluctuations using renewable energy remains a significant challenge. Electrochemical energy storage, as a highly efficient device, can serve as an important medium for storing green energy; however, it still requires high-performance electrode materials containing abundant and sustainable elements. Lithium-ion batteries are widely used in electric vehicles and smart wearable devices, demonstrating powerful driving capabilities in a mobile society. However, commercially available lithium-ion batteries for energy storage use expensive and unsustainable transition metal-based inorganic compounds, making it difficult to meet the needs of next-generation renewable electrochemical energy storage. Therefore, there is an urgent need to develop more sustainable, environmentally friendly, and economical alternative electrode materials.

[0003] Organic electrode materials for rechargeable batteries are gaining increasing attention due to their abundance, low energy consumption in production, and environmental friendliness. Furthermore, redox-active organic materials have attracted growing interest due to their inherent properties, such as structural diversity and tunable electrochemical performance. Consequently, various organic cathode materials, such as carbonyl compounds, phthalocyanines, conductive polymers, and organosulfur compounds, have emerged in electrochemical energy storage systems. Based on charge storage mechanisms, redox organic electrodes are generally classified into n-type, p-type, and bipolar electrodes according to the charge carriers of cations and anions. Compared to n-type organic electrodes, p-type organic electrode materials exhibit higher operating voltages due to the interaction between anions and the cathode. However, due to the storage of large-sized anions, p-type organic electrode materials often exhibit slow reaction kinetics, and relatively low reversible capacity is a challenge, resulting in low capacity, poor cycle performance, and limited energy density. Batteries that simultaneously provide cations and anions for charge storage are considered dual-ion batteries. In principle, this type of battery can exhibit high energy density while also possessing high discharge capacity and high operating potential.

[0004] Porphyrins are a class of aromatic macromolecules with an 18-electron configuration, widely distributed in biological systems. Due to their reactivity, porphyrins and their derivatives have seen significant development in fields such as organic solar cells and catalysis. Because of their highly conjugated structure and narrow HOMO–LUMO band gap, porphyrins exhibit rapid reaction kinetics in electrochemical reactions. In recent years, they have attracted considerable attention from researchers in the energy storage field. For example, they have been proposed as electrode materials in lithium-ion, sodium-ion, and aqueous zinc-ion batteries, as well as as additives in electrochemical energy storage electrolytes. However, the high solubility of active materials in electrolytes, leading to poor cycle stability, remains a challenge for electrochemical energy storage. Summary of the Invention

[0005] To address the issue of high solubility of organic molecules in electrochemical energy storage, this invention aims to provide a porphyrin compound, its preparation method, and its application in the cathode material of metal-ion batteries. By introducing phenothiazine or carbazole groups into the porphyrin molecule, multiple active sites are provided for the anion. Furthermore, the conjugated structure is extended after the in-situ polymerization process, significantly enhancing the structural stability of the porphyrin molecule. The resulting porphyrin compound exhibits excellent structural stability, high discharge voltage, and excellent rate performance.

[0006] To achieve the above-mentioned technical objectives, the present invention adopts the following technical solution: A porphyrin compound has the general structural formula shown in formula (I): (I) Where R is or .

[0007] The present invention also provides a method for preparing the above-mentioned porphyrin compound, comprising the following steps: Step 1: React formaldehyde with pyrrole to obtain bipyrrole; Step 2: React bipyrrole with CHO-R to synthesize a porphyrin ring, thus obtaining the porphyrin compound.

[0008] Furthermore, in step 1, the bipyrrole is synthesized from formaldehyde and pyrrole under an inert atmosphere, at a temperature of 0°C, and catalyzed by trifluoroacetic acid.

[0009] Furthermore, in step 2, the porphyrin ring is generated by bipyrrole and CHO-R under an inert atmosphere, at a temperature of 0°C, and under the action of boron trifluoride ether and dichlorocyano-p-benzoquinone.

[0010] The present invention also provides the application of the above-mentioned porphyrin compound, specifically: the porphyrin compound shown in formula (I) is thoroughly ground with a conductive agent and a binder in a solvent to obtain a positive electrode slurry, which is then coated on a current collector and vacuum dried to serve as the positive electrode. The positive electrode is then assembled with a negative electrode, an electrolyte, and a separator in an argon atmosphere to form a battery, wherein the negative electrode is one of an alkali metal, an alkaline earth metal, or an intercalable compound.

[0011] Furthermore, the conductive agent is one of conductive graphite, conductive carbon black, carbon nanotubes, or graphene; the binder is one of polytetrafluoroethylene, sodium carboxymethyl cellulose, polyvinylidene fluoride, or polyurethane; the solvent is one of N-methylpyrrolidone, ethanol, or deionized water; and the current collector is one of stainless steel foil, aluminum foil, copper foil, or nickel foil.

[0012] Furthermore, the electrolyte in the electrolyte is one of LiPF6, LiTFSI, LiFSI, LiClO4 or LiBOB, and the solvent molecule used in the electrolyte is one of ethylene carbonate (EC), propylene carbonate (PC), dimethyl carbonate (DMC) or diethyl carbonate (DEC).

[0013] Furthermore, the alkali metal ion is one of lithium, sodium, or potassium, and the alkaline earth metal ion is one of magnesium or calcium; the intercalable compound is one of metal sulfides (e.g., MoS2, TiS2, FeS2, CoS2, CuS, NiS2, VS2, etc.), metal oxides (Fe2O3, Fe3O4, TiO2, Co3O4, NiO, CuO, ZnO, etc.) or carbon-based materials (e.g., graphite, hard carbon, soft carbon, graphene, or modified graphene, etc.).

[0014] Furthermore, by mass fraction, the porphyrin compound content in the positive electrode slurry is 30-90%, the conductive agent content is 5-60%, and the binder content is 5-10%.

[0015] The present invention has the following beneficial effects: This invention provides a novel organic cathode material for metal-ion batteries. By introducing phenothiazine or carbazole functional groups onto the porphyrin molecule, these functional groups can polymerize during electrochemical oxidation, constructing a stable porphyrin polymer cathode in situ. This significantly reduces the solubility of the organic cathode, thereby achieving long-cycle stability of the cathode material. Furthermore, the phenothiazine or carbazole functional groups are intrinsically electrochemically active groups, synergistically participating in charge storage, enabling the cathode material to maintain a discharge voltage as high as 3.0V after 10,000 cycles. Attached Figure Description

[0016] Figure 1 This is a comparison diagram of the solubility of DPZP in Example 1 and DCZP in Example 2 before and after in-situ electrochemical polymerization.

[0017] Figure 2 This is the mass spectrum of DPZP in Example 1.

[0018] Figure 3 This is the infrared image of DPZP in Example 1.

[0019] Figure 4 This is the mass spectrum of DCZP in Example 2.

[0020] Figure 5 This is the infrared image of DCZP in Example 2.

[0021] Figure 6 The cyclic voltammetry curves of the DPZP cathode material in Example 1 are shown, with a scan rate of 0.2 mV / s.

[0022] Figure 7 The above are the charge-discharge curves of the DPZP cathode material in Example 1 within a voltage range of 1.8V-4.5V.

[0023] Figure 8 This is a long-cycle diagram of the DPZP cathode material in Example 1 within a voltage range of 1.8V-4.5V.

[0024] Figure 9 This is a median voltage diagram of the DPZP cathode material in Example 1 within the voltage range of 1.8V-4.5V.

[0025] Figure 10 This is a scaling factor diagram of the DCZP cathode material in Example 2 within a voltage range of 1.8V-4.5V.

[0026] Figure 11 The above are the charge-discharge curves of the DCZP cathode material in Example 2 within the voltage range of 1.8V-4.5V. Detailed Implementation

[0027] The technical solution of the present invention will be further described in detail below with reference to specific embodiments, but this does not limit the application and extension of the present invention.

[0028] Example 1

[0029] The preparation process of phenothiazine-based porphyrin compounds is as follows:

[0030] (1) Synthesis of the intermediate with chemical structural formula a: Formaldehyde (3.203 g, 40 mmol) and pyrrole (15 mL, 200 mmol) were added to a 100 mL two-necked flask, then argon gas was introduced and the mixture was stirred. After cooling to 0 °C, 0.1 mL of trifluoroacetic acid (CF3COOH) was added, and the mixture was stirred for 30 min. The reaction was then terminated by adding sodium hydroxide solution, and the mixture was stirred for 1 h. The organic and aqueous phases were separated by extraction with dichloromethane and distilled water. The obtained organic phase was purified by column chromatography (elution buffer PE:DCM = 3:1) to give white crystalline compound a (1.754 g, yield 30%).

[0031] (2) Synthesis of chemical structure b: Compound a (0.394 g, 2.7 mmol) and 4-(10H-phenothiazin-10-yl)benzaldehyde (1.229 g, 4.1 mmol) were dissolved in a 1000 mL two-necked flask. Dichloromethane (500 mL) was added, and the flask was then filled with argon and placed in an ice-water bath at 0 °C. BF3·Et2O (0.1 mL, 1.68 mmol) was added, and the mixture was stirred for 30 min. Dichlorocyano-p-benzoquinone (0.735 g, 3.2 mmol) was added to the flask, and the mixture was stirred for approximately 1 h. The volatile solvent in the organic mixture was removed under reduced pressure. Finally, the remaining organic mixture was removed, and the crude product was purified by column chromatography (eluting PE:DCM = 2:1) to obtain the crude product. The crude product was recrystallized from methanol / dichloromethane solution, and the precipitate was filtered to obtain a purple-red crystalline compound b (0.250 g, yield 22%), denoted as DPZP.

[0032] The porphyrin compound (DPZP) prepared in Example 1 was used as the positive electrode active material for lithium-ion batteries to assemble coin cells. The specific method is as follows: 10 parts by weight of DPZP, 8 parts by weight of conductive agent acetylene black, and 2 parts by weight of binder polyvinylidene fluoride were dissolved in N-methylpyrrolidone (10 mg / ml), and thoroughly ground. The uniformly ground slurry was coated onto a stainless steel sheet, and the solvent was dried in a vacuum drying oven at 110°C to serve as the positive electrode of the battery. A lithium metal sheet was used as the negative electrode, and the electrolyte was 1 mol / L LiPF6 with PC as the solvent molecule. The coin cell was assembled under an argon atmosphere, and its electrochemical performance was tested in the range of 4.5-1.8V using a constant current charge-discharge instrument.

[0033] Example 2

[0034] The preparation process of carbazole porphyrin compounds is as follows:

[0035] (1) Synthesis of the intermediate with chemical structural formula a: Same as Example 1.

[0036] (2) Synthesis of chemical structure c: Compound a (0.359 g, 2.5 mmol) and 4-(9H-carbazole-9-yl)benzaldehyde (1.003 g, 3.7 mmol) were dissolved in a 1000 mL two-necked flask. Dichloromethane (500 mL) was added, and the flask was then filled with argon and placed in an ice-water bath at 0 °C. BF3·Et2O (0.1 mL, 1.68 mmol) was added, and the mixture was stirred for 30 min. The prepared dichlorodicyano-p-benzoquinone (0.669 g, 2.9 mmol) was added to the flask, and the mixture was stirred for about 1 h. The volatile solvent in the organic mixture was removed under reduced pressure. Finally, the remaining organic mixture was removed, and the crude product was purified by column chromatography (eluting PE:DCM = 1:1) to obtain the crude product. The crude product was recrystallized from methanol / dichloromethane solution, and the precipitate was filtered to give brownish-red crystalline compound c (0.113 g, yield 11%), denoted as DCZP.

[0037] The porphyrin compound (DCZP) obtained in Example 2 was used as the positive electrode active material for lithium-ion batteries to assemble coin cells. The specific method is as follows: 10 parts by weight of DCZP, 8 parts by weight of conductive agent acetylene black, and 2 parts by weight of binder polyvinylidene fluoride were dissolved in N-methylpyrrolidone (10 mg / ml), and thoroughly ground. The uniformly ground slurry was coated onto a stainless steel sheet, and the solvent was dried in a vacuum drying oven at 80°C to serve as the positive electrode of the battery. A lithium metal sheet was used as the negative electrode, and the electrolyte was 1 mol / L LiPF6 with PC as the solvent molecule. The coin cell was assembled under an argon atmosphere, and its electrochemical performance was tested in the range of 4.5-1.8V using a constant current charge-discharge instrument.

Claims

1. A porphyrin compound, characterized in that, The general structural formula of the porphyrin compound is shown in formula (I): (I) Where R is or .

2. The method for preparing the porphyrin compound according to claim 1, characterized in that, Includes the following steps: Step 1: React formaldehyde with pyrrole to obtain bipyrrole; the structural formula of the bipyrrole is as follows: ; Step 2: React bipyrrole with CHO-R to synthesize a porphyrin ring, thereby obtaining the porphyrin compound; wherein R is... or .

3. The preparation method according to claim 2, characterized in that, In step 1, the bipyrrole is synthesized from formaldehyde and pyrrole under an inert atmosphere, at a temperature of 0°C, and catalyzed by trifluoroacetic acid.

4. The preparation method according to claim 2, characterized in that, In step 2, the porphyrin ring is generated by bipyrrole and CHO-R under an inert atmosphere, at a temperature of 0°C, and under the action of boron trifluoride ether and dichlorocyano-p-benzoquinone.

5. The application of the porphyrin compound according to claim 1 or the porphyrin compound prepared by the preparation method according to any one of claims 2-4, characterized in that, The porphyrin compound shown in formula (I) is thoroughly ground with a conductive agent and a binder in a solvent to obtain a positive electrode slurry. This slurry is then coated onto a current collector and dried under vacuum to serve as the positive electrode. It is then assembled into a battery with a negative electrode, an electrolyte, and a separator under an argon atmosphere. The negative electrode is one of an alkali metal, an alkaline earth metal, or an intercalable compound. The alkali metal is one of lithium, sodium, or potassium, and the alkaline earth metal is one of magnesium or calcium; the intercalable compound is one of metal sulfide, metal oxide, or carbon-based material.

6. The application according to claim 5, characterized in that, The conductive agent is one of conductive graphite, conductive carbon black, carbon nanotubes, or graphene; the binder is one of polytetrafluoroethylene, sodium carboxymethyl cellulose, polyvinylidene fluoride, or polyurethane; the solvent is one of N-methylpyrrolidone, ethanol, or deionized water; and the current collector is one of stainless steel foil, aluminum foil, copper foil, or nickel foil.

7. The application according to claim 5, characterized in that, The electrolyte is one of LiPF6, LiTFSI, LiFSI, LiClO4 or LiBOB, and the solvent used in the electrolyte is one of ethylene carbonate, propylene carbonate, dimethyl carbonate or diethyl carbonate.

8. The application according to claim 5, characterized in that, By mass fraction, the porphyrin compound content in the positive electrode slurry is 30-90%, the conductive agent content is 5-60%, and the binder content is 5-10%.

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