Porphyrin framework polymer as well as preparation method and application thereof

Abstract

The invention discloses a porphyrin framework polymer as well as a preparation method and application thereof. The porphyrin framework polymer is synthesized by taking tetra (5-bromothienyl) porphyrin as an intermediate, introducing thiophene substituents into four meso sites of porphyrin and then carrying out Stille coupling reaction on the porphyrin and a thiophene tin reagent. The preparation process is mild, purification is simple and convenient, the obtained polymer has high electrolyte solution solubility resistance and excellent electron conductivity, the technical problems that an organic micromolecule active material is prone to dissolution loss in an organic electrolyte, poor in conductivity and the like are effectively solved, and meanwhile the ion transmission capacity of the material is remarkably improved. The porphyrin framework polymer is used as a positive electrode active material and is matched with a metal sodium negative electrode and a NaPF6 carbonate electrolyte to assemble the battery, no obvious capacity fading is caused under 10A g <-1 > large current for about 7000 cycles, the specific capacity is high, the multiplying power and the long cycle performance are excellent, and the porphyrin framework polymer is suitable for a large-scale long-acting energy storage sodium ion battery.

Description

Technical Field

[0001] This invention relates to a method for preparing cathode materials for sodium-ion batteries, specifically to a porphyrin framework polymer, its preparation method, and its application in sodium-ion batteries. Background Technology

[0002] The large-scale development and use of fossil fuels, while driving social development, has also brought environmental pressures and increasingly tight resource reserves, making the need for energy structure transformation increasingly urgent. Although renewable energy sources such as solar, tidal, wind, and geothermal energy offer potential alternatives, their inherent intermittency and uneven geographical distribution limit their direct utilization efficiency. Therefore, constructing energy storage systems with high energy conversion efficiency has become a key path to solving the energy dilemma and realizing the large-scale application of renewable energy. Over the past few decades, lithium-ion batteries have been widely used in energy storage systems due to their high energy density, high voltage platform, fast charge and discharge response, and long-term cycle stability. In contrast, sodium-ion batteries, due to the abundant and widely distributed nature of sodium, low cost, and high energy conversion efficiency and process compatibility, are considered a potential alternative for large-scale energy storage systems. The cathode material is the core factor determining the specific capacity of lithium-ion or sodium-ion batteries.

[0003] Currently, the market for cathode materials in lithium-ion or sodium-ion batteries is mainly dominated by inorganic materials. However, these materials face the dual bottlenecks of energy density approaching theoretical limits and unsustainable mineral resources. Organic materials are considered an ideal alternative to traditional inorganic materials due to their unique comprehensive advantages, including abundant renewable resource reserves, flexible and tunable molecular structures, and simple synthesis and recycling processes. Traditional small organic molecules are easily soluble in electrolytes, leading to continuous loss of active materials and a sharp decline in capacity; at the same time, insufficient intrinsic electronic conductivity further limits their electrochemical performance. Compared to traditional small organic molecule cathode materials, organic polymer cathode materials prepared through polymerization reactions can effectively overcome the aforementioned technical defects, and therefore have received widespread attention in the field of electrochemical energy storage.

[0004] Porphyrins are a class of macrocyclic compounds with an 18π-electron aromatic conjugated system, widely distributed in nature and biological organisms. Due to their unique catalytic activity, porphyrins and their derivatives have made significant progress in the fields of organic solar cells and catalysis. Their highly conjugated molecular framework and narrow HOMO-LUMO energy level difference endow them with excellent reaction kinetics. Porphyrins with suitable functional groups can be molecularly designed to form porphyrin polymer cathode materials such as polymers, covalent organic frameworks, and metal-organic frameworks. These materials typically possess comprehensive performance advantages such as excellent solubility, high electronic conductivity, abundant redox active sites, and good structural stability, thus their application potential in the field of electrochemical energy storage has received increasing attention in recent years.

[0005] In the prior art, there are reports on the application of porphyrin polymers in the cathode of alkali metal ion batteries. For example, CN110964179B discloses a porphyrin polymer prepared by carbon-carbon triple bond coupling, which alleviates the dissolution problem of small organic molecule cathodes to some extent. However, the electronic conduction efficiency of its conjugated system constructed by alkyne bond coupling is limited, and the thiophene functionalization modification of the porphyrin meso site is not performed. Therefore, its rate performance and long-cycle stability are still difficult to meet the requirements of large-scale energy storage. CN116354971B provides a class of porphyrin compounds and applies them to the cathode of magnesium batteries. However, it is not designed for sodium-ion battery systems, and it does not construct a thiophene-based conjugated extended framework polymer structure, which cannot simultaneously achieve high conductivity and electrolyte solubility resistance. In addition, existing porphyrin-based energy storage materials generally suffer from problems such as short molecular conjugated chains, low utilization of active sites, and easy structural collapse under high temperature and high current, making it difficult to simultaneously achieve high rate, long cycle and high capacity stable output.

[0006] In summary, existing porphyrin-based cathode materials still cannot simultaneously address the three core defects of organic small molecule dissolution and loss, poor intrinsic electronic conductivity, and structural instability over long cycles, making them unsuitable for the long-term, high-stability, and low-cost requirements of sodium-ion batteries in large-scale energy storage scenarios. Therefore, developing a novel porphyrin-framework polymer cathode material with a high conjugated conductive framework, strong dissolution resistance, and excellent structural stability has become a key technical problem urgently needing to be solved in the field of organic cathodes for sodium-ion batteries. Summary of the Invention

[0007] To address the common technical problems of existing porphyrin-based cathode materials, such as low intrinsic electronic conductivity, high solubility in organic electrolytes, and unstable structure during long cycles, this invention provides a porphyrin framework polymer, its preparation method, and its application in sodium-ion batteries. The porphyrin framework polymer is synthesized by introducing thiophene substituents at the four meso positions of porphyrin and then reacting it with a thiophene-based tin reagent via a Stille coupling reaction. Using the porphyrin framework polymer as the cathode active material solves the technical problems of capacity decay and insufficient cycle stability caused by the easy solubility and poor conductivity of existing organic cathode materials.

[0008] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:

[0009] A porphyrin framework polymer has the structural formula shown in formula (I):

[0010] (I),

[0011] Where Ar is selected from , , X is selected from N, S, and O, with a degree of polymerization n of 8 to 2000, and R is one of the structures shown in formula (II):

[0012] , , (II).

[0013] Furthermore, the porphyrin framework polymer is formed by alternating covalent bonds between tetra(5-thiophene)porphyrin units and thiophene conjugated units. In the conjugated framework polymer, the porphyrin meso site forms a continuous π-conjugated system with the thiophene conjugated units through the thiophene group.

[0014] Furthermore, the tetra(5-thienyl)porphyrin unit is preferably a tetra(5-bromothien-2-yl)porphyrin derivative unit.

[0015] The preparation method of the above-mentioned porphyrin framework polymer includes the following steps:

[0016] S1, 5-bromothiophene-2-carboxaldehyde, and pyrrole undergo a coupling reaction to yield a tetra(5-bromothiophene)porphyrin intermediate, the structural formula of which is as follows:

[0017] ;

[0018] S2, a tetra(5-bromothiophenyl)porphyrin intermediate, and a bis(trimethyltinyl)thiophene compound were subjected to a Stille coupling reaction to give the final product shown in formula (I);

[0019] The bis(trimethyltinyl)thiophene compounds are selected from one of 2,5-bis(trimethyltinyl)thiophene, 2,5-bis(trimethyltinyl)thiophene[3,2-b]thiophene, and 5,5"-bis(trimethyltinyl)-2,2':5',2"-bithiophene.

[0020] The structural formula of 2,5-bis(trimethyltinyl)thiophene is:

[0021] ;

[0022] The structural formula of 2,5-bis(trimethyltinyl)thiopheneno[3,2-b]thiophene is:

[0023] ;

[0024] The structural formula of 5,5"-bis(trimethyltinyl)-2,2':5',2"-bithiophene is:

[0025] .

[0026] Further, step S1 specifically involves: using propionic acid as a solvent, mixing 5-bromothiophene-2-carboxaldehyde and pyrrole at a molar ratio of 0.9-1.1:1, reacting in an inert atmosphere at 135-155℃ for 0.5-2 hours, and then purifying by methanol precipitation and column chromatography (using petroleum ether and dichloromethane as eluents) to obtain a blue needle-like product, namely the tetra(5-bromothiophene)porphyrin intermediate.

[0027] Further, in step S2, the molar ratio of the tetra(5-bromothiophene)porphyrin intermediate to the bis(trimethyltinyl)thiophene compound is 1:1.8-2.2.

[0028] Further, in step S2, the catalyst is a composite catalytic system of tri-o-methylphenylphosphine and tris(dibenzylacetone)dipalladium, with chlorobenzene as solvent, a polymerization temperature of 120-140℃, a reaction time of 20-30 h, and then purified by washing with methanol, dichloromethane (DCM), and N,N-dimethylformamide (DMF) to obtain a black solid, which is the final product shown in formula (I).

[0029] A sodium-ion battery positive electrode includes a current collector and a positive electrode material layer loaded on the current collector. The positive electrode material layer includes the aforementioned porphyrin framework polymer, a conductive agent, and a binder.

[0030] A sodium-ion battery includes the above-mentioned positive electrode, a metallic sodium negative electrode, a separator, and a sodium-containing electrolyte.

[0031] Furthermore, the preparation process of sodium-ion batteries includes the following steps: stirring and mixing porphyrin framework polymer, conductive agent and binder in solvent to obtain a uniform positive electrode slurry, then coating the slurry onto the surface of the current collector, and drying it under vacuum to obtain a positive electrode sheet, which is then assembled into a battery with a negative electrode, electrolyte and separator under an argon atmosphere, wherein the negative electrode is a metallic sodium sheet.

[0032] Furthermore, by mass percentage, the porphyrin framework polymer accounts for 20-70%, the conductive agent accounts for 10-50%, and the binder accounts for 10-30% in the positive electrode slurry.

[0033] Furthermore, the adhesive is one of polytetrafluoroethylene, polyvinylidene fluoride, sodium carboxymethyl cellulose, and polyurethane, the solvent is N-methylpyrrolidone, and the current collector is one of stainless steel foil, aluminum foil, copper foil, and molybdenum foil.

[0034] Furthermore, the electrolyte is a carbonate electrolyte containing 0.5-2 mol / L NaPF6.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] (1) By constructing a conjugated cross-linked porphyrin framework polymer structure, this invention significantly improves the structural stability of the material in organic electrolytes, greatly reduces the dissolution and diffusion loss of active materials, fundamentally improves the rapid capacity decay caused by material dissolution, and enhances the battery cycle reliability.

[0037] (2) The present invention forms a continuous π-conjugated system by porphyrin macrocycle and thiophene unit, which effectively reduces the HOMO-LUMO energy level difference of the material and improves the intrinsic electron conduction efficiency. At the same time, the framework structure provides sufficient ion transport channels, improves sodium ion diffusion dynamics, and is suitable for high-rate charge and discharge scenarios.

[0038] (3) The present invention provides multi-electron redox sites through the synergistic effect of porphyrin ring and conjugated thiophene unit, with high utilization of active sites, and the framework structure can remain stable during sodium ion insertion and extraction, thus achieving high specific capacity output and excellent electrochemical reversibility.

[0039] (4) The cathode material prepared by this invention has both structural rigidity and electrochemical stability, and can maintain stable cycling even at high current densities. The battery capacity decays slowly during long-term cycling, for example, at MTCOP of 10 A g. -1 The initial capacity is 81mAh g. -1 It reached a peak of 156 mAh g at the 6735th cycle. -1 After nearly 7,000 cycles, there was no significant capacity loss. The overall service life and operational reliability are significantly better than traditional organic small molecule cathode materials. Attached Figure Description

[0040] Figure 1 This is the mass spectrum of FBTP in Example 1.

[0041] Figure 2 These are infrared images of FBTP and MTCOP in Example 1.

[0042] Figure 3 The cyclic voltammetry curves of the MTCOP cathode material in Example 1 are shown, with a scan rate of 0.2 mV / s.

[0043] Figure 4 These are the charge-discharge curves of the MTCOP cathode material in Example 1 within a voltage range of 1.4-4.5V.

[0044] Figure 5 This is a long-cycle diagram of the positive electrode material of MTCOP in Example 1 within a voltage range of 1.4-4.5V.

[0045] Figure 6 This is a long-cycle diagram of the positive electrode material of TTCOP in Example 2 within a voltage range of 1.4-4.5V.

[0046] Figure 7 This is a long-cycle diagram of the positive electrode material in Example 3 within a voltage range of 1.4-4.5V. Detailed Implementation

[0047] 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.

[0048] Example 1

[0049]

[0050]

[0051] (1) Synthesis of intermediate FBTP

[0052] Half (125 mL) of propionic acid was added to a 250 mL two-necked flask, followed by 2.005 g (0.01 mol) of 5-bromothiophene-2-carboxaldehyde. The mixture was then evacuated with argon gas and stirred at 145 °C in an oil pan. When the propionic acid condensed and refluxed, pyrrole (0.702 g (0.01 mol) was added. After reacting for 1 h, the reaction solution was poured into a conical flask containing 200 mL of anhydrous methanol and placed in the upper layer of a refrigerator to settle for 12 h. After filtration with anhydrous methanol, the solution was recrystallized. The solution was then subjected to column chromatography using a dry loading method with a mixed solvent of DCM:PE = 2:1 (v / v) as the eluent. A purple-red solution was obtained. The solvent was evaporated using a rotary evaporator, and the solution was recrystallized with anhydrous methanol. Finally, the solution was filtered to obtain the blue needle-like product FBTP (0.284 g, yield 11%).

[0053] Its mass spectrum is as follows Figure 1 As shown, the successful synthesis of the intermediate FBTP is demonstrated.

[0054] (2) Synthesis of porphyrin framework polymer MTCOP

[0055] FBTP (40 mg, 42 μmol), 2,5-bis(trimethyltinyl)thiophene (34.35 mg, 42 μmol), and P(o-tol)3 (tri-o-methylphenylphosphine) (4.08 mg, 13.4 μmol) were added sequentially to a 10 mL reaction flask. Then, 2.5 mL of chlorobenzene and a magnetic stir bar were added. The mixture was evacuated 2-3 times under liquid nitrogen. Tris(dibenzylacetone)dipalladium Pd2(dba)3 (1.54 mg, 1.68 μmol) was added under frozen conditions, and the mixture was degassed again 2-3 times. The mixture was stirred and reacted at 130 °C in an oil bath for 20 h (initially brick red under UV light, turning sky blue at the end of the reaction). After the reaction, the reaction solution was washed sequentially with methanol, DCM, and DMF and filtered. The resulting solid was dried in a vacuum oven at 110 °C for 3 days to obtain the black solid product MTCOP (35 mg, yield 48%).

[0056] Its infrared spectrum is as follows Figure 2 As shown, it is located at 1429cm. -1 and 1243cm -1 The absorption peaks correspond to the C=N and CN bonds of the porphyrin ring in MTCOP, respectively, at 707 cm⁻¹. -1 C-Br vibration at 2916 cm⁻¹ and 2916 cm⁻¹ -1 C at the location β The -H vibration peak weakened significantly after the polymerization process, indicating that the polymerization occurred at the α position of the thiophene group.

[0057] (3) Using porphyrin framework polymer MTCOP as positive electrode active material to fabricate sodium-ion batteries

[0058] Four parts by weight of MTCOP, four parts by weight of conductive agent acetylene black, and two 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 aluminum foil, and the solvent was dried in a vacuum drying oven at 110°C to serve as the positive electrode of the battery. A sodium metal sheet was used as the negative electrode, and the electrolyte was 1 mol / L NaPF6 with propylene carbonate (PC) as the solvent. A coin cell was assembled under an argon atmosphere, and its electrochemical performance was tested using a constant current charge-discharge instrument in the range of 1.4-4.5V at a concentration of 10.0 A g. -1 Electrochemical performance was tested using the current density.

[0059] The MTCOP obtained in Example 1 is at 0.2 mV s -1 Cyclic voltammetry curves at scan rate are as follows: Figure 3 As shown. By Figure 3As can be seen, the curves show obvious and stable redox peaks, corresponding to the multi-electron redox reaction of the porphyrin framework polymer during the sodium ion intercalation and deintercalation process. This proves that the material has good electrochemical reversibility and redox activity, and can be used as a positive electrode active material for sodium-ion batteries to stably play an electrochemical role.

[0060] The charge-discharge curves of the MTCOP obtained in Example 1 for the first three cycles within the voltage range of 1.4-4.5V are as follows: Figure 4 As shown. By Figure 4 As can be seen, the curve has a clear charge-discharge plateau, which corresponds well with the redox peaks of the cyclic voltammetry curve. The first three charge-discharge curves have a high degree of overlap and low polarization, indicating that the material has a stable structure and low electrochemical polarization during sodium ion insertion and extraction, and has excellent charge-discharge reversibility and structural stability.

[0061] Depend on Figure 5 It can be seen that the initial capacity of the MTCOP obtained in Example 1 is 81 mAh g. -1 It reached a peak of 156 mAh g at the 6735th cycle. -1 There was no significant capacity loss after nearly 7,000 cycles.

[0062] Example 2

[0063] (1) Synthesis of porphyrin framework polymer TTCOP

[0064]

[0065] FBTP (40 mg, 42 μmol), 2,5-bis(trimethylsilyl)thieno[3,2-b]thiophene (39.05 mg, 42 μmol), and P(o-tol)3 (4.08 mg, 13.4 μmol) were placed in a 10 mL reaction flask, along with 2.5 mL of chlorobenzene and a magnetic stir bar. After 2-3 cycles of liquid nitrogen freezing and vacuuming, Pd2(dba)3 (1.54 mg, 1.68 μmol) was added while the mixture was frozen, and the reaction was repeated 2-3 times. The mixture was then transferred to an oil bath at 130 °C and reacted for 20 h (the color changed from brick red to sky blue). After cooling, the mixture was washed sequentially with methanol, DCM, and DMF, filtered, and dried under vacuum at 110 °C for 3 days to obtain a black solid TTCOP (41 mg, yield 52%).

[0066] (2) Using porphyrin framework polymer TTCOP as positive electrode active material to make sodium-ion batteries

[0067] Four parts by weight of TTCOP, four parts by weight of conductive agent acetylene black, and two 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 aluminum foil, and the solvent was dried in a vacuum drying oven at 110°C to serve as the positive electrode of the battery. A sodium metal sheet was used as the negative electrode, and the electrolyte was 1 mol / L NaPF6 with PC as the solvent molecule. A coin cell battery was assembled under an argon atmosphere, and its electrochemical performance was tested in the range of 1.4-4.5V using a constant current charge-discharge instrument at a voltage of 10.0 A g. -1 Electrochemical performance was tested using the current density.

[0068] like Figure 6 As shown, the initial discharge capacity of the TTCOP obtained in Example 2 is 89 mAh g. -1 It reached its peak capacity of 147mAh g after 4690 cycles. -1 Then it began to decrease slowly.

[0069] Example 3

[0070] (1) Synthesis of porphyrin framework polymer BTCOP

[0071]

[0072] FBTP (40 mg, 42 μmol), 5,5"-bis(trimethylstanyl)-2,2':5',2"-bithiophene (39.04 mg, 42 μmol), and P(o-tol)3 (4.08 mg, 13.4 μmol) were placed in a 10 mL reaction flask, and 2.5 mL of chlorobenzene and a magnetic stir bar were added. After degassing by liquid nitrogen freezing-vacuuming-thawing cycle 2-3 times, Pd2(dba)3 (1.54 mg, 1.68 μmol) was added under frozen conditions, and the reaction was repeated by freezing and degassing 2-3 times. The mixture was then transferred to an oil bath at 130 °C and reacted for 20 h (the solution color changed from brick red to sky blue). After cooling, the mixture was washed sequentially with methanol, DCM, and DMF, filtered, and dried under vacuum at 110 °C for 3 days to obtain a black solid BTCOP (43 mg, yield 54%).

[0073] (2) Using porphyrin framework polymer BTCOP as positive electrode active material to make sodium-ion batteries

[0074] Four parts by weight of BTCOP, four parts by weight of conductive agent acetylene black, and two 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 aluminum foil, and the solvent was dried in a vacuum drying oven at 110°C to serve as the positive electrode of the battery. A sodium metal sheet was used as the negative electrode, and the electrolyte was 1 mol / L NaPF6 with PC as the solvent molecule. A coin cell battery was assembled under an argon atmosphere, and its electrochemical performance was tested in the range of 1.4-4.5V using a constant current charge-discharge instrument at a concentration of 10.0 A g. -1 Electrochemical performance was tested using the current density.

[0075] like Figure 7 As shown, the initial discharge capacity of the BTCOP obtained in Example 3 is 83 mAh g. -1 It reaches a peak capacity of 131 mAh g after 685 cycles. -1 Subsequently, the capacity began to decrease to 114mAh g after 2418 cycles. -1 After that, the capacity began to increase slowly, and stabilized at around 5000 laps.

Claims

1. A porphyrin framework polymer, characterized in that, It has the structure shown in equation (I): （I）， Where Ar is selected from , , X is selected from N, S, and O, with a degree of polymerization n of 8 to 2000, and R is one of the structures shown in formula (II): 、 、 (II)。 2. The porphyrin framework polymer as described in claim 1, characterized in that, The porphyrin framework polymer is formed by alternating covalent bonds between tetra(5-thiophene)porphyrin units and thiophene conjugated units. In the conjugated framework polymer, the porphyrin meso site forms a continuous π-conjugated system with the thiophene conjugated units through the thiophene group.

3. The porphyrin framework polymer as described in claim 2, characterized in that, The tetra(5-thienyl)porphyrin unit is a tetra(5-bromothien-2-yl)porphyrin derivative unit.

4. The method for preparing the porphyrin framework polymer according to any one of claims 1 to 3, characterized in that, Includes the following steps: S1, 5-bromothiophene-2-carboxaldehyde, and pyrrole undergo a coupling reaction to yield a tetra(5-bromothiophene)porphyrin intermediate. The structural formula of the tetra(5-bromothiophene)porphyrin intermediate is as follows: ； S2, a tetra(5-bromothiophenyl)porphyrin intermediate, and a bis(trimethyltinyl)thiophene compound were subjected to a Stille coupling reaction to give the final product shown in formula (I); The bis(trimethyltinyl)thiophene compound is selected from one of 2,5-bis(trimethyltinyl)thiophene, 2,5-bis(trimethyltinyl)thiophene[3,2-b]thiophene, and 5,5"-bis(trimethyltinyl)-2,2':5',2"-bithiophene. The structural formula of the 2,5-bis(trimethyltinyl)thiophene is: ， The structural formula of the 2,5-bis(trimethyltinyl)thiopheno[3,2-b]thiophene is: ， The structural formula of the 5,5"-bis(trimethyltinyl)-2,2':5',2"-bithiophene is: 。 5. The preparation method according to claim 4, characterized in that, Step S1 is as follows: Using propionic acid as a solvent, 5-bromothiophene-2-carboxaldehyde and pyrrole were mixed at a molar ratio of 0.9-1.1:1 and reacted in an inert atmosphere at 135-155℃ for 0.5-2 h. The product was then purified by methanol precipitation and column chromatography to obtain a blue needle-like product, namely the tetra(5-bromothiophene)porphyrin intermediate.

6. The preparation method according to claim 4, characterized in that, In step S2, the molar ratio of the tetra(5-bromothiophene)porphyrin intermediate to the bis(trimethyltinyl)thiophene compound is 1:1.8-2.

2.

7. The preparation method according to claim 4, characterized in that, In step S2, the catalyst is a composite catalytic system of tri-o-methylphenylphosphine and tris(dibenzylacetone)palladium, with chlorobenzene as solvent, a polymerization temperature of 120-140℃, and a reaction time of 20-30h. After washing and purification with methanol, dichloromethane, and N,N-dimethylformamide, a black solid is obtained, which is the final product shown in formula (I).

8. A positive electrode sheet for a sodium-ion battery, characterized in that, It includes a current collector and a positive electrode material layer loaded on the current collector, the positive electrode material layer comprising a conductive agent, a binder, and a porphyrin framework polymer as described in any one of claims 1 to 3.

9. The sodium-ion battery positive electrode sheet according to claim 8, characterized in that, By mass percentage, the porphyrin framework polymer accounts for 20% to 70% of the positive electrode material layer, the conductive agent accounts for 10% to 50%, and the binder accounts for 10% to 30%. The conductive agent is selected from one of conductive carbon black, acetylene black, graphite, graphene, and carbon nanotubes, and the binder is selected from one of polyvinylidene fluoride, polytetrafluoroethylene, sodium carboxymethyl cellulose, and polyurethane.

10. A sodium-ion battery, characterized in that, It comprises the positive electrode sheet, the sodium metal negative electrode, the separator, and the sodium-containing electrolyte as described in claim 8 or 9, wherein the electrolyte is a carbonate electrolyte containing 0.5-2 mol / L NaPF6.

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