Donor acceptor-based porous aromatic framework material and ultralow-temperature organic battery

Abstract

The invention discloses a donor-acceptor-based porous aromatic framework material and an ultralow-temperature organic battery, and belongs to the technical field of energy storage. The donor-acceptor porous aromatic framework material is marked as D-A PAF; the preparation method comprises the following steps: by taking cyclohexanehexone and 4-bromo-1, 2-phenylenediamine as raw materials, carrying out Schiff base reaction, and refluxing an obtained product and a phenazine reduction product in an organic solvent in the presence of a catalyst for 48 hours to obtain D-A PAF; the donor-acceptor porous aromatic framework material is used as a positive electrode material for preparing a potassium ion battery capable of running at low temperature. The method has the advantages of easiness in synthesis, low cost, outstanding electrochemical performance, easiness in mass production and the like.

Description

Technical Field

[0001] The present invention belongs to the field of energy storage technology and relates to a donor-acceptor porous aromatic framework containing multiple redox active sites used as a positive electrode material for a potassium ion battery. The donor-acceptor structure can promote charge transfer, thereby accelerating reaction kinetics and improving the specific capacity of the potassium ion battery. Background Art

[0002] High energy density lithium-ion batteries are currently the leading electrochemical energy storage technology, but the uneven distribution and rapid consumption of lithium resources have raised concerns about their sustainability and cost. And with the growing demand for various applications such as portable electronics, electric vehicles, and large-scale energy storage devices, rechargeable battery technology with renewable resources and high energy density has become an urgent need.

[0003] In this regard, due to the high natural abundance of potassium (1.5%, lithium is 0.0017%) and the lower K + / K potential, potassium ion batteries have attracted more and more research interests. And based on the smaller Stokes radius and lower solvation energy, potassium ion batteries are more adaptable to changes in operating temperature and achieve fast kinetics at low temperatures. However, K + With a larger diameter ( Lithium ion ) and heavier mass. This large size K + Repeated insertion / extraction of organic electrodes can lead to severe volume changes and slow electrode kinetics of inorganic electrode materials. In contrast, organic electrode materials have been widely used in various rechargeable metal-ion batteries (lithium, zinc, aluminum ion batteries, etc.) in recent years due to their flexible structural designability, high level of functionality and environmental friendliness. Built-in groups in organic molecules such as C=N, C=O, N=N can serve as reactive active sites for metal ion storage. Considering the problem of easy dissolution of organic small molecule electrodes in organic electrolytes, the fixation of redox active groups into porous two-dimensional or three-dimensional (2D or 3D) frameworks has been widely explored and proved to be an effective strategy to obtain more reliable electrodes.

[0004] As an emerging porous material, porous aromatic framework (PAF) exhibits a wealth of excellent properties, such as light weight, customized pore structure and adjustable skeleton structure. The porous aromatic framework is composed of a rich set of aromatic units. Its modular structure and high structural stability make it have potential applications in storage, sensing, catalysis and other fields. When such materials are used as electrode materials, the porous aromatic framework obtained by the donor-acceptor design concept can promote charge transfer, accelerate reaction kinetics, and thus improve capacity performance. The donor structural units mainly include phenothiazine, phenazine, triphenylamine, thiophene, pyrene, tetrathiafulvalene, etc. The acceptor structural units mainly include triazine, hexaazatriazine, pyrenetetraketone, anthraquinone, anhydride, phthalocyanine, porphyrin, benzothiazole, etc. Summary of the invention

[0005] The present invention aims to improve the problems of low capacity, poor cycle stability and unstable rate performance that are common in most current potassium ion battery electrode materials, and provides a porous aromatic framework material that can be used as a positive electrode material for a potassium ion battery and a preparation method thereof.

[0006] The above technical problems are solved by the following technical solutions:

[0007] A donor-acceptor porous aromatic framework material, denoted as DA PAF, has the following structure:

[0008]

[0009] A method for preparing a donor-acceptor porous aromatic framework material comprises the following steps:

[0010] 1) Compound 1 and Compound 2 were used as raw materials, and the mixture was refluxed in an acetic acid solution for 40 hours to synthesize Compound 3, wherein Compound 1 was cyclohexanone, and Compound 2 was 4-bromo-1,2-phenylenediamine; the structural formula of Compound 3 was as follows:

[0011]

[0012] 2) Compound 4 was used as a raw material, and compound 5 was synthesized by sodium dithionite reduction reaction in a mixed solution of ethanol and water for 3 hours. Compound 4 is phenazine; the structural formula of compound 5 is as follows:

[0013]

[0014] 3) Compound 3, compound 5, potassium carbonate and palladium acetate are refluxed in an organic solvent for 48 hours, and the reaction is carried out in an inert gas atmosphere to obtain compound 6, i.e. the donor-acceptor porous aromatic framework material; the organic solvent is toluene.

[0015] Preferably, in step 1), the molar ratio of compound 1 to compound 2 is 1:4, and the entire reaction is carried out in an inert gas atmosphere.

[0016] Preferably, in step 2), the reaction is carried out in an inert gas atmosphere, and the entire reaction process is avoided from contact with air to prevent the product from being oxidized.

[0017] Preferably, in step 3), the molar ratio of compound 3 to compound 5 is 2:3.

[0018] An ultra-low temperature organic battery is a potassium ion battery using the donor-acceptor porous aromatic framework material (DA PAF) as a positive electrode material, and is prepared according to the following steps:

[0019] 1) DA PAF, acetylene black and PVDF were added with solvent NMP (N-methylpyrrolidone) in a mass ratio of 6:3:1 and ground into a uniform slurry, which was then coated on aluminum foil using a coating machine;

[0020] 2) drying the coated aluminum foil in an oven at 80°C for 12 hours to remove the residual solvent;

[0021] 3) Cutting the electrode sheet dried in step 2) into circular electrode sheets with a diameter of 12 mm for later use;

[0022] 4) Battery assembly: Use 2025 button cells, put circular electrode sheets, diaphragms, electrolytes, potassium sheets, gaskets, springs, and positive electrode shells in the negative electrode shell in sequence, and then use a packaging machine to package them to obtain potassium ion 2025 button cells, and then use the Blue Electric / Newway battery testing system for constant current charge and discharge tests.

[0023] Preferably, in step 4), the electrolyte is a KPF6 solution in ethylene glycol dimethyl ether with a concentration of 1 mol / L and a volume of 100 uL, and the diaphragm is a glass fiber membrane.

[0024] Beneficial effects:

[0025] 1. The DA PAF synthesized in the present invention has multiple redox centers and exhibits high specific capacity and good stability as a positive electrode material for potassium ion batteries. -1 At a current density of 210 mAh g -1 The specific capacity is about 30A. -1 At a current density of , it can continue to cycle 11,000 times without obvious attenuation.

[0026] 2. DA PAF as a positive electrode material for potassium ion batteries can show good reversible specific capacity under low temperature conditions. At -20℃, 200mAg -1It can show 170mAh g -1 At -40℃, 200mAg -1 It can show 140mAh g -1 At -80℃, 50mAg -1 It can show 75mAh g -1 The specific capacity is about .

[0027] 3. The DA PAF material synthesized in the present invention is easy to synthesize, has low cost, outstanding electrochemical performance, and is easy to mass produce. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 FTIR image of the donor-acceptor porous aromatic framework DA PAF;

[0029] Figure 2 NMR images of the donor-acceptor porous aromatic framework DA PAF;

[0030] Figure 3 is the XRD pattern of the donor-acceptor porous aromatic framework DA PAF;

[0031] Figure 4 SEM image of the donor-acceptor porous aromatic framework DA PAF;

[0032] Figure 5 Donor-acceptor porous aromatic framework DA PAF as cathode material for potassium-ion batteries at 200 mAh g -1 Charge and discharge curves under current density;

[0033] Figure 6 The rate diagram of the donor-acceptor porous aromatic framework DA PAF as a cathode material for potassium ion batteries;

[0034] Figure 7 Donor-acceptor porous aromatic framework DA PAF as cathode material for potassium-ion batteries at 30 A g -1 Cycle diagram under current density;

[0035] Figure 8 The cyclic voltammetry curve of the donor-acceptor porous aromatic framework DA PAF as a positive electrode material for potassium ion batteries;

[0036] Fig. 9 Impedance diagram of the donor-acceptor porous aromatic framework DA PAF as a positive electrode material for potassium ion batteries.

[0037] Fig.10The donor-acceptor porous aromatic framework DA PAF as a cathode material for potassium ion batteries has a 200 mAg -1 Cycle diagram under current density.

[0038] Fig.11 The donor-acceptor porous aromatic framework DA PAF as a cathode material for potassium ion batteries has a 50 mA g / min at -80 °C -1 Cycle diagram under current density. DETAILED DESCRIPTION

[0039] The present invention provides a donor-acceptor porous aromatic framework material (DA PAF), which has multiple redox active sites and can be used as an electrode material for an organic potassium ion battery. The synthesis route of the DA PAF is as follows:

[0040] Compound 3 was synthesized by refluxing cyclohexanone (denoted as compound 1) and 4-bromo-1,2-phenylenediamine (denoted as compound 2) in acetic acid.

[0041]

[0042] Compound 4 is refluxed with sodium dithionite in a mixed solution of ethanol and water to obtain compound 5.

[0043]

[0044] Compound 3, compound 5, potassium carbonate and palladium acetate are refluxed in an organic solvent to obtain compound 6 (DA PAF), wherein the organic solvent is toluene and a toluene solution of tri-tert-butylphosphine (1 mol / L).

[0045]

[0046] Example 1

[0047] 1) Cyclohexanone (312 mg, 1 mmol) and 4-bromo-1,2-phenylenediamine (748 mg, 4 mmol) were added with anhydrous acetic acid (60 mL) under a nitrogen atmosphere and then refluxed for 40 h. After cooling to room temperature, the mixture was poured into water, filtered and thoroughly washed with deionized water and ethanol to remove excess acid, and a light green solid (recorded as compound 3) was collected. Finally, the obtained product was dried in vacuo at 80 °C.

[0048] 2) Compound 4 (6 g, 33.3 mmol) was dispersed in 150 mL of ethanol and heated to reflux under a nitrogen atmosphere. Then, sodium dithionite (58 g, 333 mmol) dissolved in 600 mL of water was added at once and heated to reflux for 3 h. After cooling to room temperature, the solid was filtered and thoroughly washed with deionized water to collect the light blue solid (recorded as compound 5). Finally, the obtained product was dried under vacuum at 80 °C.

[0049] 3) A mixture of compound 3 (364 mg, 0.6 mmol), compound 5 (164 mg, 0.9 mmol) and potassium carbonate (1.3 g, 9.406 mmol) was added to a two-necked flask, and toluene (50 mL) was added thereto under a nitrogen atmosphere. After the mixture was heated to 80°C, palladium acetate (26.3 mg, 0.117 mmol) and a toluene solution of tri-tert-butylphosphine (1 mL) were added, and the reaction system was stirred at 120°C under nitrogen for 48 h.

[0050] 4) After the obtained mixture is cooled to room temperature, the solid is filtered and then washed with hot water and methanol. Finally, the solid is washed in water, methanol, dichloromethane and acetone respectively by Soxhlet extraction method, and vacuum dried at 80°C overnight to obtain a dark red powder solid, which is the donor-acceptor porous aromatic framework material DA PAF. The obtained material is characterized by FTIR, NMR, XRD, and SEM. The results are as follows Figures 1 to 4 As shown, it was proved that DA PAF was successfully synthesized.

[0051] Example 2

[0052] The DA PAF synthesized in Example 1 was used as the positive electrode material of the potassium ion battery to prepare a potassium ion battery: HATNPZ, acetylene black, and PVDF were added with NMP in a mass ratio of 6:3:1 and ground into a uniform slurry, and then coated on an aluminum foil using a coating machine, and then placed in an oven at 80°C for 14 hours to remove the residual solvent, and cut into circular electrode sheets with a diameter of 12 mm for standby use; using the 2025 button battery standard, a circular electrode sheet, a diaphragm, an electrolyte, a potassium sheet, a gasket, a shrapnel, and a positive electrode shell were placed in the negative electrode shell in sequence, and a potassium ion 2025 button battery was obtained after packaging, and then a constant current charge and discharge test was performed using the Blue Electric / Newway battery testing system.

[0053] Depend on Figure 5 It can be seen from the charge and discharge curves that the battery prepared by the present invention has a high -1 The current density was 210 mAh g -1 The specific capacity, at the same time, Figure 6 The rate performance of DA PAF electrode at different current densities is given. When the current density reaches 5Ag -1When the capacity is still up to 190mAh g -1 When the current returns to 200mAg -1 When the capacity is 30Ag, the capacity can return to the initial capacity. -1 The stability of the battery was tested at a current density of Figure 7 As shown in Figure 2, the capacity has hardly decayed after 11,000 cycles. Figure 8 The CV curves shown in the figure show five pairs of obvious redox peaks, representing a multi-step redox process, and at high potential, a clear PF6 - In order to study the kinetic behavior of the battery, the battery was tested for impedance. The results are as follows: Fig. 9 As shown in the figure, after 200 cycles, the impedance value is still very low, which shows that DA PAF has good electrochemical kinetics, which may give it excellent electrochemical performance. The electrochemical performance of DA PAF in low temperature environment was further tested. Fig.10 The cycling curves show that DA PAF at -20℃ and -40℃ is 200mAg -1 The current density was 170 mAh g -1 and 140mAh g -1 The battery performance was further tested at an extreme temperature of -80°C. Fig.11 As shown, at 50mAg -1 The current density was 75 mAh g -1 Specific capacity.

Claims

1. A donor-acceptor porous aromatic framework material, denoted as DA PAF, has the following structure:

2. A method for preparing the donor-acceptor porous aromatic framework material according to claim 1, comprising the following steps: 1) Compound 1 and Compound 2 were used as raw materials, and the mixture was refluxed in an acetic acid solution for 40 hours to synthesize Compound 3, wherein Compound 1 was cyclohexanone, and Compound 2 was 4-bromo-1,2-phenylenediamine; the structural formula of Compound 3 was as follows: 2) Compound 4 was used as a raw material, and compound 5 was synthesized by sodium dithionite reduction reaction in a mixed solution of ethanol and water for 3 hours. Compound 4 is phenazine; the structural formula of compound 5 is as follows: 3) Compound 3, compound 5, potassium carbonate and palladium acetate are refluxed in an organic solvent for 48 hours, and the reaction is carried out in an inert gas atmosphere to obtain compound 6, i.e. the donor-acceptor porous aromatic framework material; the organic solvent is toluene.

3. The method for preparing a donor-acceptor porous aromatic framework material according to claim 2, characterized in that: In step 1), the molar ratio of compound 1 to compound 2 is 1:4, and the entire reaction is carried out in an inert gas atmosphere.

4. The method for preparing a donor-acceptor porous aromatic framework material according to claim 2, characterized in that: In step 2), the reaction is carried out in an inert gas atmosphere and the reaction is avoided from contact with air during the entire reaction process to prevent the product from being oxidized.

5. The method for preparing a donor-acceptor porous aromatic framework material according to claim 2, characterized in that: In step 3), the molar ratio of compound 3 to compound 5 is 2:

3.

6. An ultra-low temperature organic battery is a potassium ion battery using the donor-acceptor porous aromatic framework material of claim 1 as a positive electrode material, prepared by the following steps: 1) DA PAF, acetylene black and PVDF were added with solvent N-methylpyrrolidone in a mass ratio of 6:3:1 and ground into a uniform slurry, which was then coated on aluminum foil using a coating machine; 2) drying the coated aluminum foil in an oven at 80°C for 12 hours to remove the residual solvent; 3) Cutting the electrode sheet dried in step 2) into circular electrode sheets with a diameter of 12 mm for later use; 4) Battery assembly: Use 2025 button cells, put circular electrode sheets, diaphragms, electrolytes, potassium sheets, gaskets, springs, and positive electrode shells in the negative electrode shell in sequence, and then use a packaging machine to package them to obtain potassium ion 2025 button cells.

7. The ultra-low temperature organic battery according to claim 6, characterized in that: In step 4), the electrolyte is a 1 mol / L KPF6 solution in ethylene glycol dimethyl ether, with a volume of 100 uL, and the diaphragm is a glass fiber membrane.

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