Preparation method and application of electrode material

Abstract

The invention discloses a conjugated organic lithium ion battery electrode material as well as a preparation method and application thereof, and belongs to the technical field of lithium ion batteries. Firstly, a compound 1 is subjected to acid hydrolysis to synthesize a compound 2, the compound 2 reacts with TFA, NaNO2, NaHCO3 and NaOH and then reacts with HCl to obtain H6-HAT, excessive lithium hydroxide is added for reaction, and finally the derivative Li6-HAT of 1, 4, 5, 8, 9, 12-hexaazabenzophenanthrene (HAT) is obtained. When the conjugated organic electrode material Li6-HAT is used for a lithium ion battery electrode, the first discharge specific capacity reaches 1126 mAh / g under the current density of 0.01-3 V and 100 mA / g; and the discharge capacity after circulation is 588.0 mAh / g after 50 times of circulation. The conjugated organic electrode material synthesized by the invention is novel and stable in structure, and is a novel lithium ion battery electrode material.

Description

[0001] This invention is a divisional application. The name of the original application is "A conjugated organic lithium-ion battery electrode material, its preparation method and application", the application number is 202010264736.5, and the application date is April 7, 2020. Technical Field

[0002] The present invention relates to the technical field of lithium ion batteries, and in particular to a conjugated organic lithium ion battery electrode material, a preparation method and an application thereof. Background Art

[0003] Lithium-ion batteries have played an important role in the development of portable electronic devices and are considered the most promising energy technology for the next generation of electric vehicles. However, the widespread use of lithium-ion batteries also brings environmental challenges, such as metal pollution and the greenhouse effect, which means that the development of environmentally friendly and sustainable electrode materials to replace traditional graphite anodes and inorganic metal oxide cathodes is urgent.

[0004] Organic materials offer a wide range of options due to their environmental friendliness, redox stability, abundance, and safety. Organic electrodes possess excellent charge storage capacity due to the presence of appropriate functional groups that are electrochemically active toward lithium ions, and their HOMO / LUMO energies can be easily engineered at the molecular level. In recent years, many types of organic materials have emerged, such as organic radical compounds, organosulfur compounds, carbonyl compounds, quinone / phenolate derivatives, and conductive polymers, all of which have been used as electrode materials for high-performance lithium-ion batteries.

[0005] However, the dissolution of organic compounds in Li-based electrolytes can lead to rapid capacity decay during charge / discharge. Therefore, to enhance the stability in electrolytes, the cycling stability of organic compounds can be enhanced by (1) covalently linking electroactive organic molecules to the conductive backbone, such as carbon black; (2) polymerizing redox-active compounds to reduce dissolution; and forming salts with organic carboxylic acid compounds, such as terephthalate. Although these strategies can effectively inhibit the dissolution of organic compounds in Li-based electrolytes, a large amount of carbon is still required to offset the low electronic conductivity of the organic compounds, which reduces the energy density of the organic electrodes. Therefore, it is crucial to explore new organic compounds with high energy density and excellent cycling stability. Summary of the Invention

[0006] The purpose of the present invention is to provide a conjugated organic lithium-ion battery electrode material and its preparation method and application to solve the problems existing in the above-mentioned prior art. The conjugated organic lithium-ion battery electrode material has high energy density and excellent cycle stability, novel and stable structure, and is a new type of lithium-ion battery electrode material.

[0007] To achieve the above object, the present invention provides the following solutions:

[0008] The present invention provides a conjugated organic lithium-ion battery electrode material, wherein the electrode material is a 1,4,5,8,9,12-hexaazatriphenylene derivative, and its molecular structure is as follows:

[0009]

[0010] The present invention also provides a method for preparing a conjugated organic lithium-ion battery electrode material, comprising the following steps: 1) using compound 1 as a raw material and synthesizing compound 2 through acid hydrolysis;

[0011]

[0012] 2) Compound 2 reacts with TFA and NaNO2 in the presence of AcOH, then EtOH solvent is added, followed by further reaction with NaHCO3 and NaOH, and finally, HCl is added and reacted at 90°C to obtain H6-HAT;

[0013] 3) The obtained H6-HAT is dissolved in an ethanol solution, and an excess amount of lithium hydroxide solution is added to react to obtain a Li6-HAT compound.

[0014] Furthermore, in step 1), the acid involved in the acid hydrolysis of compound 1 is concentrated sulfuric acid, the hydrolysis temperature is room temperature, and the hydrolysis time is 72 hours.

[0015] Furthermore, in step 2), the reaction temperature of compound 2 with TFA and NaNO2 is room temperature, the reaction time is 72h, the reaction temperature with NaHCO3 and NaOH is room temperature, the reaction time is 12h, the amount of HCl added is 6N, and the reaction time is 1h.

[0016] Furthermore, in step 2), the mass ratio of TFA to compound 2 is 50:1, and the molar ratio of compound 2 to NaNO2 is 1:9.

[0017] Furthermore, in step 3), the reaction temperature of H6-HAT and lithium hydroxide solution is room temperature, and the reaction time is 48 hours.

[0018] The present invention also provides an application of the conjugated organic lithium ion battery electrode material or the conjugated organic lithium ion battery electrode material prepared by the preparation method in a lithium ion battery electrode.

[0019] The present invention discloses the following technical effects:

[0020] Heteroatom-containing π-conjugated aromatic compounds possess a pair of electrons and exhibit excellent redox activity, making them promising electrode materials for lithium-ion batteries. Inspired by the design of extended π-conjugated organic semiconductor molecules in organic electronics, where extended π-conjugated molecules can stabilize the −1 and +1 charge states and facilitate charge transport, nitrogen-containing heteroaromatic compounds (e.g., azo compounds), pteridines, and indigo carmine have been demonstrated as promising anodes for lithium-ion batteries. Furthermore, extended π-conjugated molecules can enhance intermolecular interactions (π-π interactions), thereby improving electronic conductivity and reducing solubility in lithium-based electrolytes.

[0021] The conjugated organic lithium-ion battery electrode material of the present invention is a π-conjugated N-containing heteroaromatic hexacarboxylate (Li6-HAT) molecule, which is a derivative of 1,4,5,8,9,12-hexaazatriphenylene (HAT). The conjugated organic lithium-ion battery electrode material Li6-HAT is used for lithium-ion battery electrodes. Through electrochemical performance testing, the results show that at a current density of 0.01V-3V and 100mA / g, the initial discharge specific capacity reaches 1126mAh / g, and the discharge capacity after 50 cycles is 588.0mAh / g. The preparation method of the present invention has low requirements for synthesis equipment. The synthesized conjugated organic electrode material has high energy density and excellent cycle stability, novel structure and stable performance, and is a new type of lithium-ion battery electrode material. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0023] Figure 1 The structural diagram and surface electrostatic potential diagram of conjugated organic lithium-ion battery electrode material Li6-HAT;

[0024] Figure 2 The structural diagram and XRD pattern of Li6-HAT, a conjugated organic lithium-ion battery electrode material;

[0025] Figure 3 This is the infrared spectrum of the conjugated organic lithium-ion battery electrode material Li6-HAT;

[0026] Figure 4 This is the XPS elemental spectrum of conjugated organic lithium-ion battery electrode material Li6-HAT;

[0027] Figure 5This is the XPS-C1s spectrum of the conjugated organic lithium-ion battery electrode material Li6-HAT;

[0028] Figure 6 This is the XPS-Ns spectrum of the conjugated organic lithium-ion battery electrode material Li6-HAT;

[0029] Figure 7 This is the XPS-O1s spectrum of the conjugated organic lithium-ion battery electrode material Li6-HAT;

[0030] Figure 8 This is the SEM image of the conjugated organic lithium-ion battery electrode material Li6-HAT;

[0031] Figure 9 TEM image of conjugated organic lithium-ion battery electrode material Li6-HAT;

[0032] Figure 10 HRTEM image of conjugated organic lithium-ion battery electrode material Li6-HAT;

[0033] Figure 11 This is the first charge and discharge curve of the conjugated organic lithium-ion battery electrode material Li6-HAT;

[0034] Figure 12 This is the 50th charge-discharge curve of the conjugated organic lithium-ion battery electrode material Li6-HAT;

[0035] Figure 13 This is the 50-cycle curve of the conjugated organic lithium-ion battery electrode material Li6-HAT;

[0036] Figure 14 This is the 500-cycle curve of the conjugated organic lithium-ion battery electrode material Li6-HAT. DETAILED DESCRIPTION

[0037] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0038] It should be understood that the terms described herein are intended only to describe particular embodiments and are not intended to limit the present invention. In addition, for numerical ranges herein, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Each smaller range between any intermediate value within a stated value or stated range and any other stated value or intermediate value within the stated range is also encompassed by the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded within the scope.

[0039] Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may also be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of any conflict with any incorporated document, the contents of this specification shall prevail.

[0040] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments described herein without departing from the scope or spirit of the invention. Other embodiments will be apparent to those skilled in the art from the description of the invention. The present description and examples are intended to be illustrative only.

[0041] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0042] The present invention provides a conjugated organic lithium-ion battery electrode material, wherein the electrode material is a 1,4,5,8,9,12-hexaazatriphenylene derivative, and its molecular structure is as follows:

[0043]

[0044] The method for preparing the above-mentioned conjugated organic lithium-ion battery electrode material comprises the following steps:

[0045]

[0046] 1) Compound 1 was hydrolyzed in the presence of concentrated sulfuric acid at room temperature for 72 h to synthesize compound 2;

[0047] 2) Compound 2 was reacted with TFA and NaNO2 in the presence of AcOH at room temperature for 72 h, wherein the mass ratio of TFA to compound 2 was 50:1, and the molar ratio of compound 2 to NaNO2 was 1:9. EtOH solvent was then added and the reaction was continued with NaHCO3 and NaOH at room temperature for 12 h. Finally, 6N HCl was added and the reaction was carried out at 90°C for 1 h to obtain H6-HAT;

[0048] 3) The obtained H6-HAT was dissolved in an ethanol solution, and an excess of lithium hydroxide solution was added, and the mixture was reacted at room temperature for 48 hours to obtain a Li6-HAT compound.

[0049] Example 1

[0050] The synthesis route of conjugated organic lithium-ion battery electrode material Li6-HAT is as follows:

[0051]

[0052] Here are the steps:

[0053] 1) Add 400 g of concentrated sulfuric acid to 10 g of compound 1, stir and react at room temperature for 72 h, filter after completion of the reaction, wash the filtered solid with deionized water three times, then wash with acetone three times, and then dry under vacuum at 100 degrees for 14 h to obtain compound 2, with a product yield of more than 87%;

[0054] 2) 4.92 g of compound 2 was added to 150 mL of trifluoroacetic acid (TFA) and stirred at room temperature. 7.0 g of sodium nitrite (NaNO2) was then added and reacted at room temperature. The mass ratio of TFA to compound 2 was 50:1, and the molar ratio of compound 2 to NaNO2 was 1:9. After completion of the reaction, a brown suspension was obtained. 150 mL of acetic acid was added, stirred for 12 h, poured into 300 mL of ice water, and filtered to obtain a solid product. The solid product was dissolved in 150 mL of NaHCO3 solution, stirred and filtered to remove insoluble solids to obtain a filtrate; 30 mL of EtOH solvent was added, the filtrate was treated with activated carbon, heated to boiling, and filtered to obtain a clear yellow solution. The solution was then treated with cold sodium hydroxide (20.0 g in 100 mL of water) to obtain HAT. HAT was suspended in water according to the solid-liquid ratio of HAT to water (2.52 g / 40 mmol): 100 mL, heated to 50°C, and acidified by adding 6N concentrated HCl. The resulting mixture was reacted at 90°C for 1 h, then filtered to obtain the initial product, washed with 10% HCl (3×25 mL), and finally washed with deionized water (2×25 mL), and then dried in vacuo at 120°C to obtain H6-HAT.

[0055] 3) H6-HAT was dissolved in an ethanol solution, an excess of lithium hydroxide aqueous solution was added, and the reaction was stirred at room temperature for 48 hours. After the reaction was completed, the mixture was filtered, washed with deionized water three times, washed with ethanol three times, and dried at 50 degrees to a constant weight to obtain a conjugated organic lithium-ion battery electrode material Li6-HAT.

[0056] Figure 1 This is the structural diagram and surface electrostatic potential diagram of the conjugated organic lithium-ion battery electrode material Li6-HAT.

[0057] The obtained conjugated organic lithium-ion battery electrode material Li6-HAT was subjected to morphology analysis, XRD analysis, infrared spectrum analysis and XPS elemental analysis.

[0058] The structure and XRD pattern of conjugated organic lithium-ion battery electrode material Li6-HAT are shown in Figure 2 .

[0059] The infrared spectrum of conjugated organic lithium-ion battery electrode material Li6-HAT is shown in Figure 3 .

[0060] The XPS spectrum of conjugated organic lithium-ion battery electrode material Li6-HAT is shown in Figure 4-7 .

[0061] The morphology analysis of conjugated organic lithium-ion battery electrode material Li6-HAT is shown in Figure 8-10 .

[0062] Performance testing of conjugated organic lithium-ion battery electrode material Li6-HAT:

[0063] A mixture of Li6-HAT, PVDF, and KS6 was prepared in a mass ratio of 60:10:30. NMP was added as a solvent and stirred for 2 hours to prepare a lithium-ion battery electrode slurry. The viscous electrode slurry was coated onto 12μm copper foil to a thickness of 50μm and dried at 100°C for 12 hours to obtain a lithium-ion battery electrode.

[0064] The lithium-ion battery negative electrode was cut into a circular piece with a diameter of 14 mm, and the lithium metal counter electrode used a 15 mm diameter lithium metal sheet. The electrolyte consisted of 1 mol / L LiPF6 dissolved in a solvent of ethylene carbonate (EC) and dimethyl carbonate (DMC) (molar ratio EC:DMC = 1:1). The cells were assembled into 2032-type button cells in an argon-filled glove box.

[0065] The prepared button battery was charged and discharged. At a current density of 100 mA / g, the first charge and discharge curve of the conjugated organic lithium-ion battery electrode material Li6-HAT was shown in Figure 2. Figure 11 ,Depend on Figure 11 It can be seen that at 0.01V-3V and a current density of 100mA / g, the first discharge specific capacity of Li6-HAT reaches 1126mAh / g.

[0066] Figure 12 The 50th charge and discharge curve of Li6-HAT at a current density of 100 mA / g.

[0067] It can be seen that at 0.01V-3V and a current density of 100mA / g, the 50th discharge specific capacity of Li6-HAT can still be as high as 588mAh / g.

[0068] Figure 13 This is the 50-cycle curve of Li6-HAT at a current density of 100 mA / g. Calculated from the second discharge capacity, the capacity retention rate after 50 cycles is 72%.

[0069] Figure 14 This is the 500 cycle curve of Li6-HAT at a current density of 800mA / g.

[0070] Depend on Figure 14 It can be seen that after 500 cycles, the capacity retention rate of Li6-HAT is 87.2%, which shows excellent cycle stability.

[0071] The embodiments described above are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should fall within the scope of protection determined by the claims of the present invention.

Claims

1. A method for preparing an electrode material, characterized in that: The electrode material is a 1,4,5,8,9,12-hexaazatriphenylene derivative, and the preparation method comprises the following steps: 1) Compound 2 was synthesized by acid hydrolysis using compound 1 as raw material; 2) Compound 2 reacts with TFA and NaNO2 in the presence of AcOH, then EtOH solvent is added, followed by further reaction with NaHCO3 and NaOH, and finally, HCl is added and reacted at 90°C to obtain H6-HAT; 3) The obtained H6-HAT is dissolved in an ethanol solution, and an excess amount of lithium hydroxide solution is added to react to obtain a Li6-HAT compound.

2. An electrode material, characterized in that Prepared by the preparation method as claimed in claim 1.

3. Use of the electrode material as claimed in claim 2 in lithium ion battery electrodes.

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