Covalent organic frameworks and energy storage devices

Abstract

A covalent organic framework comprising a plurality of aromatic moieties, each aromatic moieties being linked by at least one thioether bond, and a method for preparing the covalent organic framework. An energy storage device comprising a battery having electrodes comprising a covalent organic framework.

Description

Technical Field

[0001] This invention relates to a covalent organic framework. It also relates to an energy storage device. Background Technology

[0002] For decades, lithium-ion batteries (LIBs) have been widely commercialized due to their superior performance; however, they are expensive and pose safety concerns. Sodium-ion batteries (SIBs) are widely considered a potential alternative to LIBs as a solution to these problems. However, obtaining high-performance cathode materials remains a major obstacle to improving the capacity of SIBs.

[0003] Compared to inorganic electrode materials, organic electrode materials are regenerable, can be designed for specific functions, and have higher theoretical specific capacity. Some small organic molecules with active groups exhibit excellent device performance when used as cathode materials for SIBs. However, because they are soluble in electrolytes, their capacity decreases significantly from the second cycle onwards, which is detrimental to achieving long-term battery stability. Summary of the Invention

[0004] In a first aspect, a covalent organic framework is provided, comprising: a plurality of aromatic moieties, each aromatic moiety being linked by at least one thioether bond. Preferably, each of the plurality of aromatic moieties is linked by two thioether bonds.

[0005] Optionally, each of the plurality of aromatic moieties includes at least one carbonyl group, and preferably includes two carbonyl groups.

[0006] Optionally, each of the plurality of aromatic moieties is a benzoquinone moiety. The covalent organic framework may include a plurality of disulfide-linked benzoquinone moieties.

[0007] In a second aspect, an electrode is provided that includes a covalent organic framework, which may be the covalent organic framework of the first aspect. The electrode may also include a conductive material, a binder, and a current collector.

[0008] In a third aspect, an energy storage device is provided, comprising a battery having electrodes comprising a covalent organic framework, which may be the covalent organic framework of the first aspect.

[0009] Optionally, the covalent organic framework also includes multiple redox active sites for facilitating ion diffusion in energy storage devices. These multiple redox active sites may include sulfur atoms in a thioether bond.

[0010] Optionally, each of the plurality of aromatic moieties includes at least one carbonyl group, and the plurality of redox active sites include the carbonyl group.

[0011] Optionally, the electrode is a cathode. The battery can be rechargeable and can be in the form of a button cell. Optionally, the battery can include a sodium-ion battery or a lithium-ion battery.

[0012] In a fourth aspect, a method for preparing a covalent organic framework is provided, comprising the steps of: forming a mixture of an aromatic compound and a thiol, degassing the mixture, and heating the degassed mixture.

[0013] Optionally, the aromatic compound includes benzoquinone, such as halobenzoquinone. For example, halobenzoquinone is 2,3,5,6-tetrachloro-1,4-benzoquinone or 2,3,5,6-tetrafluoro-1,4-benzoquinone.

[0014] Alternatively, the thiol is an aromatic thiol, such as 1,2,3,4,5,6-benzenehexathiol.

[0015] Optionally, the mixing step includes mixing a base and a solvent with an aromatic compound and a thiol to form a mixture, wherein the base includes any one of sodium carbonate, potassium carbonate, cesium carbonate, sodium hydroxide, sodium methoxide, and N,N-diethylethylamine, and the solvent includes any one of 1,2-dichlorobenzene, n-butanol, 1,4-dioxane, mesitylene, N-methylpyrrolidone, N,N-dimethylacetamide, or mixtures thereof.

[0016] Optionally, the method further includes ultrasonicating the mixture to form a homogeneous mixture.

[0017] Optionally, the degassing step includes performing at least one freeze-vacuum-thaw cycle on the mixture, and preferably three freeze-vacuum-thaw cycles.

[0018] In a fifth aspect, a method for manufacturing an energy storage device is provided, comprising the steps of: assembling components of the energy storage device in a predetermined order within a larger housing and a smaller housing, and bonding the larger housing and the smaller housing together with a pressure of about 0.1 kPa to about 1.5 kPa.

[0019] Other features and characteristics of the invention will be readily apparent from the detailed description and accompanying drawings. Any feature described herein with respect to one aspect or embodiment may be combined with any other feature described herein with respect to any other aspect or embodiment, where appropriate and applicable. Attached Figure Description

[0020] Embodiments of the invention will now be described by way of example with reference to the accompanying drawings, in which:

[0021] Figure 1 This is a schematic diagram illustrating the synthesis of a covalent organic framework (hereinafter referred to as BHT-BQ-COF) according to an embodiment of the present invention;

[0022] Figure 2 This is a schematic exploded view of an energy storage device according to an embodiment of the present invention;

[0023] Figure 3 The Fourier transform infrared (FT-IR) spectra of the precursor, model compound, and BHT-BQ-COF are shown.

[0024] Figure 4 Thermogravimetric curve of BHT-BQ-COF;

[0025] Figure 5 Cyclic voltammetry (CV) curves of a sodium-ion battery based on a BHT-BQ-COF electrode are shown for the first three cycles, with a voltammetry of 0.1 mV / s over a voltage range from 0.1 V to 3.5 V. -1 The scanning speed is obtained;

[0026] Figure 6 Voltage-capacity curves of a sodium-ion battery based on a BHT-BQ-COF electrode are shown during the first, fifth, and tenth cycles.

[0027] Figure 7A For 200mA g -1 A graph showing the capacity and coulombic efficiency of a sodium-ion battery based on a BHT-BQ-COF electrode as a function of cycle number at a given current density.

[0028] Figure 7B For 400mA g -1 A graph showing the capacity and coulombic efficiency of a sodium-ion battery based on a BHT-BQ-COF electrode as a function of cycle number at a given current density.

[0029] Figure 8 For 100mA g -1 Up to 5000mA g -1 Graphs showing the capacity and coulombic efficiency of sodium-ion batteries based on BHT-BQ-COF electrodes as a function of cycle number over a wide current density range and a voltage range of 0.1V to 3.5V; and

[0030] Figure 9 Electrochemical impedance spectroscopy (EIS) curves of Na / / BHT-BQ-COF sodium-ion batteries under different charging and discharging states are shown in a wide frequency range from 100 kHz to 100 mHz. Detailed Implementation

[0031] Before explaining any embodiments of the invention in detail, it should be understood that the application of the invention is not limited to the structural details and component arrangements set forth in the following description or shown in the following figures. The invention is capable of having other embodiments and can be implemented or performed in various ways. Furthermore, it should be understood that the phrases and terms used herein are for descriptive purposes and should not be considered limiting. Those skilled in the art will understand that terms of degree such as “generally” or “approximately” refer to a reasonable range beyond a given value, for example, general tolerances associated with the manufacture, assembly, testing, and use of the described embodiments.

[0032] In one embodiment, a covalent organic framework (COF) is provided, comprising a plurality of aromatic moieties, each aromatic moieties being linked by at least one thioether bond. In a preferred embodiment, the COF comprises a dithioether linkage. As used herein, a “covalent organic framework” refers to an organic crystalline porous material that integrates molecular structural units (i.e., aromatic moieties) linked by covalent bonds and integrated into a periodic structure, which can extend to two or three dimensions. In one embodiment, the COF may have a porous rigid structure.

[0033] Those skilled in the art will understand that, due to their purely covalent and metal-free structure, COFs typically exhibit excellent chemical stability in organic solvents and can withstand harsh conditions (e.g., acidic and alkaline conditions) to maintain their ordered structure and crystallinity. Therefore, the COFs in this embodiment can be used for gas separation and storage, heterogeneous catalysis, chemical sensing, luminescence, electronic devices, drug delivery, and energy storage and conversion.

[0034] As used in this article, "aromatic fraction" includes substituted or unsubstituted C 3-8 cycloalkyl, substituted or unsubstituted C 3-8 Cycloalkenyl, substituted or unsubstituted 3- to 8-membered heterocyclic alkyl, substituted or unsubstituted 3- to 8-membered heterocyclic alkenyl, substituted or unsubstituted C 6-10 aryl, substituted or unsubstituted C 7-11 The aromatic moiety comprises any one of an aryl group, a substituted or unsubstituted heteroaryl group having 5 to 10 carbon atoms or heteroatoms. Preferably, the aromatic moiety includes at least one carbonyl group, such as a benzoquinone moiety having two carbonyl groups.

[0035] A "thioether bond" refers to a covalent bond connecting structural units, including RS-R' bonds, where R is one of a plurality of aromatic moieties, and R' is an adjacent aromatic moiety or a functional group connected to an adjacent aromatic moiety. A "dithioether bond" refers to two thioether bonds, namely the two RS-R' bonds connecting a pair of aromatic moieties. The functional group of R' can be a substituted or unsubstituted C group. 3-8 cycloalkyl, substituted or unsubstituted C3-8 Cycloalkenyl, substituted or unsubstituted 3- to 8-membered heterocyclic alkyl, substituted or unsubstituted 3- to 8-membered heterocyclic alkenyl, substituted or unsubstituted C 6-10 aryl, substituted or unsubstituted C 7-11 Any one of an aralkyl group, or a substituted or unsubstituted heteroaryl group having 5 to 10 carbon atoms or heteroatoms. Preferably, the bond between the aromatic moieties is a benzenehexathiol group.

[0036] In one embodiment, the COF can be prepared from an aromatic compound and a thiol. For example, the aromatic compound can be benzoquinone, more preferably a halobenzoquinone. The thiol can be an aromatic thiol having at least one thioether bond for forming at least one thioether bond in the COF.

[0037] A method for preparing COF may include the following steps: forming a mixture of an aromatic compound and a thiol, degassing the mixture, and heating the degassed mixture.

[0038] The mixing step can involve a condensation or cross-coupling reaction between the aromatic compound and the thiol. For example, the mixing step can be carried out in a reaction vessel specifically designed for gas-sensitive chemical reactions (e.g., a Schlenk flask or tube). The mixing step can also include mixing a base and a solvent with the aromatic compound and the thiol to form a mixture. The base can be any of sodium carbonate, potassium carbonate, cesium carbonate, sodium hydroxide, sodium methoxide, and N,N-diethylethylamine. The solvent can be any of 1,2-dichlorobenzene, n-butanol, 1,4-dioxane, mesitylene, N-methylpyrrolidone, N,N-dimethylacetamide, or mixtures thereof.

[0039] After the mixing step and before the degassing step, the method may further include sonicating the mixture to form a homogeneous mixture. For example, the mixture may be sonicated for about 1 minute to about 30 minutes, about 3 minutes to about 15 minutes, or about 5 minutes to about 12 minutes.

[0040] Those skilled in the art should understand that dissolved gases (such as oxygen, carbon dioxide, etc.) that may hinder chemical reactions involving sensitive reagents, interfere with spectroscopic measurements, or cause unnecessary bubble formation are removed from the mixture during the degassing step.

[0041] In one embodiment, the degassing step includes performing at least one freeze-vacuum-thaw cycle on the mixture, which involves (i) freezing the mixture, (ii) applying a vacuum to the frozen mixture, and then (iii) sealing and heating the mixture. Specifically, the mixture in the reaction vessel is first sealed to prevent inert gases from entering the vessel when it is frozen in, for example, liquid nitrogen or dry ice used to bring the mixture to a temperature of about 80 K. Once the mixture in the vessel is frozen, the vessel can be unsealed while maintaining a vacuum for about 1 minute to about 20 minutes, about 3 minutes to about 15 minutes, or about 5 minutes to about 10 minutes to allow the headspace to evacuate. The vessel can remain immersed in liquid nitrogen or dry ice during the vacuum application. The vessel can then be resealed under vacuum and removed from the liquid nitrogen or dry ice to allow the mixture to reach room temperature. This may also involve using a heat source to accelerate the heating of the mixture. When the mixture thaws, dissolved gases escape into the headspace. This process can be repeated 10, 5, or 3 times to remove unwanted dissolved gases.

[0042] Alternatively or additionally, the degassing step may involve heating, ultrasonic stirring, chemical degassing, bubbling with inert gas, etc.

[0043] The method may then proceed to the step of heating the degassed mixture, for example, at about 30°C to about 300°C, about 40°C to about 200°C, or about 60°C to about 130°C for about 24 hours to about 120 hours, about 48 hours to about 96 hours, or about 72 hours. The heated mixture is then allowed to cool to room temperature before being filtered, washed (e.g., with water, dimethylformamide, tetrahydrofuran, and dichloromethane), and dried to obtain COF. Without considering theoretical constraints, the synthesis in this example is considered to achieve a product yield of about 65% to about 85%.

[0044] In a preferred embodiment, the COF is BHT-BQ-COF, which is composed of a plurality of disulfide-linked benzoquinone moieties. Figure 1 The synthesis of BHT-BQ-COF is illustrated, involving a cross-coupling reaction between a halobenzoquinone and an aromatic thiol. In the illustrated examples, the aromatic thiol is 1,2,3,4,5,6-benzenehexathiol (BHT), and the halobenzoquinone is a tetrahalobenzoquinone (THBQ), such as 2,3,5,6-tetrafluoro-1,4-benzoquinone (TFBQ) or 2,3,5,6-tetrachloro-1,4-benzoquinone (TCBQ). The aromatic thiol and haloquinone are mixed with sodium carbonate as a base and n-butanol as a solvent before degassing and heating at 120°C for 72 hours.

[0045] As described above, COF can be used in energy storage applications. More specifically, COF can be used as an electrode (e.g., cathode) in rechargeable energy storage devices (e.g., sodium-ion or lithium-ion batteries). The sulfur atoms of the thioether bond and the carbonyl groups of the quinone moiety provide redox active sites, and its porous, rigid structure facilitates ion diffusion (e.g., ion insertion and extraction) and provides excellent stability of the electrode in the electrolyte, thereby maximizing the device's capacity and providing excellent reversibility.

[0046] Figure 2 An exemplary energy storage device 20 is shown, which uses COF as the cathode. The energy storage device 20 shown is in the form of a button cell. The button cell 20 includes a housing having a larger housing 22 (e.g., a positive electrode housing) and a smaller housing 24 (e.g., a negative electrode housing). Components within the housing include, assembled in the following order: an O-ring 26 adjacent to the smaller housing 24, a spring 28, a gasket 30, an anode 32, a separator 34, and an electrolyte, and a cathode 36 adjacent to the larger housing 22, having a cast film closer to the anode 32. The gasket 30 may be a stainless steel gasket. The anode 32 may be a metal component, such as a metal foil, a metal disc, etc. The gasket 30 and the anode 32 may be coupled together before assembling the button cell 20. The separator may be placed closer to the anode than the gasket and may be made of glass fiber. The electrolyte can be a liquid, gel, or solid electrolyte, such as sodium bis(fluorosulfonyl)imide (NaFSI), sodium bis(trifluoromethanesulfonyl)imide (NaTFSI), or sodium hexafluorophosphate (NaPF6). The electrolyte may also include a solvent, such as diethylene glycol dimethyl ether or 1-methyl-1-propylpyrrolidine bis(trifluoromethanesulfonyl)imide (py13TFSI). Preferably, the electrolyte has the above-described substance at a concentration of about 0.5 M to about 4.0 M in the solvent.

[0047] The cathode 36 may include COF, a conductive material, a binder, and a current collector. The conductive material may include conductive carbon, such as Super P, Ketjen Black, or carbon nanotubes. The binder may include polyvinylidene fluoride (PVDF). The current collector may be copper foil or aluminum foil. The cathode 36 is preferably positioned as centrally as possible to the anode 32 to avoid uneven current density.

[0048] In one embodiment, the preparation of the cathode 36 includes the following steps: mixing COF, conductive material, binder, and solvent (e.g., N-methyl-2-pyrrolidone (NMP)) to form a slurry, applying the slurry to a current collector, and drying the assembly. Preferably, the mass ratio of COF, conductive material, and binder in the slurry is from about 7:2:1 to about 3:6:1. The drying step may be carried out in a vacuum oven at about 30°C to about 150°C, about 50°C to about 130°C, or about 60°C to about 120°C for about 3 hours to about 48 hours, about 5 hours to about 36 hours, or about 6 hours to about 24 hours.

[0049] In one embodiment, the fabrication of the energy storage device 20 includes the following steps: assembling the components of the device 20 in the order described above, and bonding the larger housing 22 to the smaller housing 24 at a pressure of about 0.1 kPa to about 1.5 kPa, about 0.5 kPa to about 1.0 kPa, or about 0.75 kPa to about 0.85 kPa. The assembly steps may sequentially include the following steps: pressing the anode 32 against the gasket 30, placing the O-ring 26 and pressing it against the smaller housing 24, placing the spring 28 on top, then placing the gasket 30 and the anode 32 (with the anode 32 facing upwards), placing the separator 34 as centrally as possible, dropping the electrolyte (e.g., about 100 μL to about 300 μL) onto the separator 34, placing the cathode 36 on top (with the cast film facing the anode 32), and placing the larger housing 22 on top.

[0050] The invention will now be described in more detail by way of examples, but the invention is not limited thereto.

[0051] Unless otherwise specified, all tests herein were conducted under standard conditions, including room and test temperature of 25°C, sea level (1 atm) pressure, pH 7, and all measurements are in metric units. Furthermore, unless otherwise specified, all percentages, ratios, etc., herein are by weight. It should be understood that, unless otherwise specified, the materials, compounds, chemicals, etc., described herein are generally commodities and / or industry standards available from a variety of suppliers worldwide. Unless otherwise specified, all reagents and solvents were used without further purification. n-Butanol, 1,2-dichlorobenzene, and 1,4-dioxane were purchased in ultra-dry grades with a water content of less than 50 ppm.

[0052] Example 1

[0053] Synthesis of BHT-BQ-COF

[0054] In a Schlenk tube, 1,2,3,4,5,6-benzenehexathiol (BHT, 40.0 mg), 2,3,5,6-tetrachloro-1,4-benzoquinone (TCBQ, 54.5 mg), sodium carbonate (122.3 mg), and n-butanol (2 mL) were added. The mixture was frozen to 78 K in a liquid nitrogen bath and evacuated for 10 minutes, then sealed and heated to room temperature. After two more freeze-evacuation-thawing cycles, the mixture was heated to 120 °C and reacted for 72 hours. The crude product was filtered and washed with water, dimethylformamide, tetrahydrofuran, and dichloromethane, and dried to give a brown solid (49.4 mg, 79.5%).

[0055] Example 2

[0056] Synthesis of benzo[5,6][1,4]dithio[2,3-b]thionethane-6,13-dione (model compound)

[0057] Benzene-1,2-dithiol (100 mg, 0.7 mmol), 2,3,5,6-tetrachloro-1,4-benzoquinone (72 mg, 0.3 mmol), and potassium carbonate (249 mg, 1.8 mmol) were added to a flask. After evacuation and argon filling, N,N'-dimethylformamide (5 mL) was added and the mixture was stirred at 90 °C for 24 hours. The product was purified by column chromatography to give a reddish-brown solid (81 mg, 70%).

[0058] Example 3

[0059] Characterization of BHT-BQ-COF and model compounds

[0060] To verify the formation of disulfide bonds in BHT-BQ-COF, Fourier transform infrared (FTIR) spectra of the BHT-BQ-COF precursor (i.e., 1,2,3,4,5,6-benzenehexathiol (BHT) and 2,3,5,6-tetrachloro-1,4-benzoquinone (TCBQ)), BHT-BQ-COF of Example 1, and the model compound of Example 2 were measured. The FTIR spectra were obtained using a PerkinElmer Spectrum Two FTIR spectrometer. Figure 3 As shown, in BHT-BQ-COF, the -SH bond of BHT (approximately 2500 cm⁻¹) -1 The disappearance of the -CS bond (703 cm⁻¹) indicates complete conversion of the precursor after the coupling reaction. -1 and 664cm -1 ) and == CSC key (1233cm -1 and 1028cm -1 The presence of ) indicates the formation of disulfide bonds, which respectively interact with the model compound at 705 cm⁻¹. -1 658cm -11243cm -1 and 1030cm -1 The peaks correspond to each other.

[0061] The thermal stability of BHT-BQ-COF was determined using a ceramic pan on a PerkinElmer STA 6000. Figure 4 Thermogravimetric analysis showed that BHT-BQ-COF retains over 90% of its initial weight when the temperature reaches 230℃. This indicates that BHT-BQ-COF exhibits good thermal stability.

[0062] Example 4

[0063] Preparation of BHT-BQ-COF cathode

[0064] BHT-BQ-COF, Ketjen Black, and polyvinylidene fluoride (PVDF) were mixed in N-methyl-2-pyrrolidone (NMP) at a mass ratio of 5:4:1 to form a slurry. The resulting slurry was coated onto aluminum foil and dried in a vacuum oven at 80°C for 12 hours.

[0065] Example 5

[0066] Preparation of sodium-ion half-cells

[0067] First, the sodium sheet is pressed onto the stainless steel gasket. Then, an O-ring is placed on the smaller housing and pressed down. Next, the spring, the assembled stainless steel gasket, and the sodium sheet are placed sequentially on the O-ring, with the sodium sheet facing upwards. Then, the separator (glass fiber) is placed as centrally as possible on the sodium sheet. Next, 200 μL of a 1 M sodium hexafluorophosphate (NaPF6) diethylene glycol dimethyl ether solution is dropped onto the separator as the electrolyte. Next, the BHT-BQ-COF-based cathode obtained in Example 4 is placed on top, with the membrane containing the active material facing the sodium sheet and placed as centrally as possible to avoid uneven current density. Finally, the larger housing is placed on top, and the button cell is coupled with a pressure of 0.8 kPa.

[0068] Example 6

[0069] Electrochemical performance of sodium-ion half-cells

[0070] First, the CR2032 button cells were assembled in an argon-filled glove box (O2 ≤ 0.1 ppm, H2O ≤ 0.1 ppm). These button cells were used to study the electrochemical performance of the sodium-ion half-cells obtained in Example 5, with Na foil as the counter electrode (Na / / BHT-BQ-COF SIB). Figure 5 Cyclic voltammetry (CV) curves for the sodium-ion half-cell are shown. CV measurements were performed on a Zahner electrochemical workstation at voltages ranging from 0.1 V to 3.5 V and 0.1 mVs.-1 The scan rate is used. For example... Figure 5 As shown, the broad peak at 0.1 V to 1.0 V during the first reduction reaction is attributed to the formation of the solid electrolyte interface (SEI) on the electrode surface. The redox peaks at 2.23 / 2.13 and 2.82 / 2.74 V demonstrate the reversible redox reaction of the BHT-BQ-COF electrode.

[0071] Figure 6 The voltage-capacity curves of a sodium-ion battery based on a BHT-BQ-COF electrode are shown during the first, fifth, and tenth cycles. The figure illustrates the voltage-capacity curves at a current density of 20 mA g / g. -1 At that time, the reversible specific capacity of the BHT-BQ-COF-based electrode in SIB reached approximately 350 mAh g. -1 This indicates that BHT-BQ-COF has abundant redox active sites.

[0072] Battery cycling tests were performed on a MACCOR battery cycler at 100, 200, 400, 500, 800, 1000, 1500, 2000, 3000, and 5000 mA g. -1 Constant current charge-discharge measurement at current density. Figure 7A and Figure 7B The figures show the results at a current density of 200 mAg. -1 and 400mA g -1 High cycling stability, with a reversible capacity of 290 mAh g. -1 and 282mAh g -1 This is closely related to the stable structure of BHT-BQ-COF. Figure 8 The BHT-BQ-COF-based electrode was shown at 100 mA g. -1 Up to 5000mA g -1 Excellent rate performance over a wide current density range and a voltage range of 0.1V to 3.5V demonstrates the rapid Na+ conversion in the electrode material. + Diffusion kinetics.

[0073] Figure 9 Electrochemical impedance spectroscopy (EIS) curves of the Na / / BHT-BQ-COF half-cell under different charge-discharge states are shown. These EIS spectra were obtained by applying a 10 mV sinusoidal wave within the 100 kHz to 100 mHz frequency range using a Solartron 1400 electrochemical workstation. Figure 9 As shown, charge-transfer resistance (R) ct() corresponds to a semicircle at high frequencies. After the Na / / BHT-BQ-COF battery undergoes a charge and discharge process, R ct The stable and small values ​​indicate that it has rapid reaction kinetics on the electrode surface. + It can diffuse rapidly, giving BHT-BQ-COF-based electrodes excellent rate performance.

[0074] The above embodiments and examples provide a disulfide-linked COF that exhibits better stability in electrolytes compared to typical small organic molecules. Its porous, rigid structure, ease of modification, and insolubility make it a promising organic cathode material for rechargeable sodium-ion batteries. When combined with appropriate electrolytes and additives (e.g., additives providing multiple redox active sites), it can simultaneously achieve high capacity and excellent cycle stability and reversibility. The COF also possesses a large specific surface area, which facilitates efficient ion insertion and extraction.

[0075] Those skilled in the art will understand that various changes and / or modifications can be made to the specific embodiments shown in this invention without departing from the spirit or scope of the broad description of the invention. Therefore, the described embodiments of the invention should be considered illustrative in all respects, and not restrictive.

Claims

1. A covalent organic framework, characterized in that, The covalent organic framework comprises a plurality of benzoquinone moieties linked by hexabenzenehexathiol groups, and includes the following structure: 。 2. An energy storage device, characterized in that, The energy storage device includes a battery having electrodes, the electrodes comprising a covalent organic framework according to claim 1.

3. The energy storage device according to claim 2, characterized in that, The covalent organic framework also includes multiple redox active sites for promoting ion diffusion in the energy storage device.

4. The energy storage device according to claim 3, characterized in that, The plurality of redox active sites include the sulfur atom of the benzene hexathiol group and the carbonyl group of the benzoquinone moiety.

5. The energy storage device according to any one of claims 2 to 4, characterized in that, The electrode is a cathode.

6. The energy storage device according to any one of claims 2 to 4, characterized in that, The battery is rechargeable.

7. The energy storage device according to any one of claims 2 to 4, characterized in that, The battery includes a sodium-ion battery or a lithium-ion battery.

8. The energy storage device according to any one of claims 2 to 4, characterized in that, The energy storage device is in the form of a button cell battery.

9. A method for preparing the covalent organic framework according to claim 1, characterized in that, The method includes the following steps: A mixture is formed with 2,3,5,6-tetrachloro-1,4-benzoquinone or 2,3,5,6-tetrafluoro-1,4-benzoquinone and 1,2,3,4,5,6-benzenehexathiol; The mixture is degassed; and The mixture after heating and degassing.

10. The method according to claim 9, characterized in that, The mixing step includes mixing a base and a solvent with the 2,3,5,6-tetrachloro-1,4-benzoquinone or 2,3,5,6-tetrafluoro-1,4-benzoquinone, and the 1,2,3,4,5,6-benzenehexathiol to form the mixture, wherein the base includes any one of sodium carbonate, potassium carbonate, cesium carbonate, sodium hydroxide, sodium methoxide, and N,N-diethylethylamine, and the solvent includes any one of 1,2-dichlorobenzene, n-butanol, 1,4-dioxane, mesitylene, N-methylpyrrolidone, N,N-dimethylacetamide, or mixtures thereof.

11. The method according to claim 9, characterized in that, The method further includes ultrasonic treatment of the mixture to form a homogeneous mixture.

12. The method according to claim 9, characterized in that, The degassing step includes performing at least one freeze-vacuum-thaw cycle on the mixture.

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