A tetrazapentacene derivative, its preparation method and application in a lithium-ion battery

Abstract

The present invention belongs to the field of organic electrode materials, and discloses a tetrazapentacene derivative, a preparation method thereof, and an application thereof in a lithium ion battery. Aiming at the problem of performance attenuation caused by dissolution of the tetrazapentacene derivative organic electrode material, the present invention utilizes the conductivity and adsorption of the carbon-based material to provide a dyeing and fixing method strategy. Through the effective composite of the tetrazapentacene derivative and the carbon-based material, not only can the dissolution of small molecules be effectively inhibited, the stability of the electrode material be improved, but also the rate performance of the electrode material can be improved. This preparation method of the composite electrode material does not require the addition of a binder and a conductive agent, can realize the firm anchoring of the nitrogen-containing aromatic ring organic molecule on the carbon substrate material, has a simple and easy-to-operate preparation process, low cost, is suitable for mass production, and at the same time contributes new ideas to the development of flexible electrodes based on organic materials.

Description

Technical Field

[0001] The present invention belongs to the field of electrode materials for metal ion batteries, and relates to a tetrazapentacene derivative, a preparation method thereof, and an application as an electrode material in a lithium ion battery. Background Art

[0002] With the continuous development of society, the market demand for lithium ion batteries will continue to expand. Against this background, metal mineral resources related to lithium ion batteries have become the focus of worldwide attention and competition. From a long-term development perspective, current secondary batteries based on non-renewable mineral resources will face the problem of resource shortage. Therefore, it is of great significance to develop new electrode materials with high specific capacity, low cost, high stability, and green safety. Organic electrode materials are generally composed of elements abundant in nature (C, H, O, N, S), can be obtained from biomass or synthesized under mild conditions, and have the advantages of low cost, environmental friendliness, and resource sustainability. More importantly, organic electrode materials have molecular designability and can be designed purposefully according to the requirements of battery performance.

[0003] Among them, organic electrode materials based on the reaction of carbon-nitrogen double bonds (C=N) have been widely reported for their application as electrode materials due to their structural diversity, functional tunability, and excellent electrochemical performance. Nitrogen atoms, as electrochemically active sites, can undergo reversible redox reactions. During the discharge process, the C=N double bond opens and reacts with metal ions, showing high specific capacity. However, for many organic small molecule electrode materials, their solubility in the electrolyte is very large. The dissolved active substances not only cannot effectively undergo reversible redox reactions, but may also migrate to the lithium metal negative electrode through the electrolyte, leading to a series of side reactions, resulting in a continuous increase in the irreversible capacity of the battery and serious safety hazards. These problems have hindered the practical application process of organic nitrogen heterocyclic electrode materials. Therefore, it is of great significance to develop metal ion batteries based on nitrogen heterocyclic electrode materials with good cycle stability and high rate performance. Summary of the Invention

[0004] Aiming at the problem of performance degradation caused by dissolution of the above-mentioned organic electrode materials, by using the electrical conductivity and adsorption of carbon-based materials, the present invention provides a dyeing and fixing method strategy. The effective composite of the tetrazapentacene derivative and the carbon cloth can not only effectively inhibit the dissolution of small molecules and improve the stability of the electrode material, but also improve the rate performance of the composite electrode material. The electrode prepared by the composite of the organic molecular material and the carbon cloth can also be applied to flexible wearable devices, contributing new research ideas and directions to the development of flexible electrodes based on organic materials.

[0005] The tetrazapentacene derivative described in the present invention has the following general structural formula:

[0006]

[0007] Among them, the R1-R4 groups can each independently be selected from one of hydrogen, halogen, methyl, methoxy, carboxyl or sulfonic acid group.

[0008] The preparation method of the tetrazapentacene derivative includes the following steps:

[0009] (1) Under the protection of an inert gas, 2,5-dihydroxy-1,4-benzoquinone and o-phenylenediamine derivative A are added to a reactor, dissolved in an organic or aqueous solvent, and the reaction mixture is continuously stirred under reflux at 100°C - 120°C for 24 hours to obtain 2,3-(R1, R2)-7,8-dihydrophenazine;

[0010] (2) The 2,3-(R1, R2)-7,8-dihydrophenazine prepared in step (1) and o-phenylenediamine derivative B are dissolved in an organic solvent, and the reaction mixture is continuously stirred under reflux at 100°C - 120°C for 24 - 36 hours; after the reaction is completed, the reaction solution is cooled to room temperature, the solid is collected by suction filtration, washed several times with acetone and ethanol respectively, and finally dried in vacuo at 100 - 120°C for 24 - 30 hours to obtain a black solid.

[0011] The synthesis reaction equation involved in the present invention is as follows:

[0012]

[0013] In step (1), the structure of o-phenylenediamine derivative A is: The R1, R2 groups can each independently be selected from one of hydrogen, halogen, methyl, methoxy, carboxyl or sulfonic acid group;

[0014] In step (2), the structure of o-phenylenediamine derivative B is: The R3, R4 groups can each independently be selected from one of hydrogen, halogen, methyl, methoxy, carboxyl or sulfonic acid group;

[0015] Among them, the molar ratio of o-phenylenediamine derivative A to 2,5-dihydroxy-1,4-benzoquinone is 1:1; the molar ratio of o-phenylenediamine derivative B to 2,3-(R1, R2)-7,8-dihydrophenazine is 5 - 6:1.

[0016] Among them, the organic solvent is one of ethanol and ethylene glycol methyl ether.

[0017] Among them, the inert gas is one of nitrogen and argon.

[0018] The preparation steps of a tetrazapentacene composite electrode material are as follows:

[0019] Step (1): Cut a piece of carbon cloth, ultrasonically clean it to remove surface impurities. Take a certain amount of concentrated sulfuric acid and concentrated nitric acid, mix them evenly, and perform pretreatment on the carbon cloth. The volume ratio of the two is 1:1. Carry out a hydrothermal reaction at 80 - 120 °C for 4 - 8 h. After the reaction ends and the reaction kettle cools to room temperature, take out the treated carbon cloth and repeatedly rinse it with ultrapure water to remove the residual concentrated acid on the carbon cloth.

[0020] The purpose of this step is to expose the surface of carbon fibers on the carbon cloth, increase its specific surface area, introduce more acidic groups on the carbon cloth surface, and change the properties of the carbon substrate.

[0021] Step (2): Dissolve the tetrazapentacene derivative solid in an acidic aqueous solution, add the carbon cloth treated in step (1), stir well, then let it stand for 2 - 4 h. Then add a strong base solution to adjust the pH to alkaline, and a solid will precipitate and adhere to the surface of the carbon fiber. Take out the carbon cloth composite electrode, wash it several times with deionized water, dry it in vacuum at 100 - 120 °C for 36 - 48 h, and then cut it to prepare the positive electrode sheet.

[0022] In step (2), the acidic aqueous solution is one of formic acid, acetic acid, and hydrochloric acid, and the concentration is 3 - 5 M.

[0023] In step (2), the dissolution of the tetrazapentacene derivative solid in the acidic aqueous solution needs to be carried out under sufficient stirring to ensure that the concentration of the active substance in the solution is close to the saturation state.

[0024] In step (2), the strong base solution is one of sodium hydroxide solution or potassium hydroxide solution, and the concentration is 3 - 5 M.

[0025] In step (2), the dropping rate of the strong base solution is controlled at 0.02 ml - 0.03 ml per minute until the pH of the system is 10 - 14.

[0026] The present invention also provides an application of the tetrazapentacene composite electrode material in a metal ion battery.

[0027] The metal ion battery includes a tetrazapentacene composite positive electrode, and also includes the negative electrode material, separator, and electrolyte. The negative electrode material includes metallic lithium or metallic sodium, the separator is a glass fiber membrane or a PP separator, and the electrolyte is lithium hexafluorophosphate or sodium hexafluorophosphate dissolved in one or a mixture of two or more of ester solvents such as ethylene carbonate, propylene carbonate, dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, and fluoroethylene carbonate.

[0028] Compared with the existing technology, the beneficial effects of the present invention are as follows:

[0029] The organic electrode material of the tetrazapentacene derivative of the present invention uses conventional drugs, the product preparation method is simple, the raw materials used are green and cheap, and the problem of performance attenuation caused by dissolution of the organic molecular electrode material is successfully solved through effective compounding with carbon cloth. When applied to lithium-ion batteries, it shows good electrochemical cycle stability and rate performance. Different from the existing lithium battery electrode preparation process, the composite electrode preparation method described in the present invention simplifies the electrode design and preparation process, omits the traditional slurry preparation link, does not require the addition of binders and conductive agents, and can realize the firm anchoring of nitrogen-containing aromatic ring organic molecules on the carbon cloth substrate by modifying the properties of the carbon material substrate surface through pretreatment, and successfully constructs an integrated flexible electrode. The preparation process is simple and easy to operate, with low cost and suitable for mass production. Description of the Drawings

[0030] Figure 1 It is the proton nuclear magnetic resonance spectrum of the liquid of DHTAP obtained in Example 1.

[0031] Figure 2 It is the Fourier transform infrared spectrum of DHTAP obtained in Example 1.

[0032] Figure 3 It is the X-ray diffraction pattern of DHTAP obtained in Example 1.

[0033] Figure 4 It is the scanning electron microscope of the carbon cloth dyed with DHTAP prepared in Example 2.

[0034] Figure 5 It is the charge-discharge curve of the battery obtained with the carbon cloth dyed with DHTAP prepared in Example 2 as the positive electrode sheet (current density is 0.05 A / g).

[0035] Figure 6 It is the cyclic voltammogram of the battery assembled based on the DHTAP-dyed carbon cloth electrode.

[0036] Figure 7 It is the comparison of the charge-discharge curves of the battery assembled based on the DHTAP-dyed carbon cloth electrode and the DHTAP battery obtained by the traditional preparation method (current density is 0.05 A / g).

[0037] Figure 8 It is the comparison of the cycle stability of the battery assembled based on the DHTAP-dyed carbon cloth electrode and the DHTAP battery obtained by the traditional preparation method (current density is 0.1 A / g).

[0038] Figure 9Comparison of the rate performance of the battery assembled based on the DHTAP-dyed carbon cloth electrode with that of the DHTAP battery obtained by the traditional preparation method (the current densities are 0.05, 0.1, 0.2, 0.4, 0.8, 1.6, and 3.2 A / g respectively).

[0039] Figure 10 It is the Fourier transform infrared spectrum of DHTAP-4Cl obtained in Example 3.

[0040] Figure 11 It is the charge-discharge curve of the battery assembled based on the DHTAP-4Cl electrode (the current density is 0.1 A / g).

[0041] Figure 12 It is the cycle life of the battery assembled based on the DHTAP-4Cl electrode (the current density is 0.05 A / g). Detailed implementation mode

[0042] To make the technical objectives, technical solutions, and beneficial effects of the present invention clearer, the technical solutions of the present invention will be further described below with reference to the attached drawings and specific embodiments.

[0043] Example 1:

[0044] Under the protection of inert gas, 0.9 g (6.4 mmol) of 2,5-dihydroxy-1,4-benzoquinone and 4.2 g (38.9 mmol) of o-phenylenediamine were successively added to a three-necked flask. Using 50 mL of ethylene glycol methyl ether as the solvent, the reaction was refluxed at 120 °C with continuous stirring for 48 h. After the reaction was completed, it was cooled to room temperature. The purple-black solid was collected by suction filtration, washed 3 times with acetone and ethanol respectively, and finally vacuum dried at 120 °C for 24 h to obtain the black solid 5,14-dihydro-5,7,12,14-tetraazapentacene (DHTAP). The synthesis reaction equation is as follows:

[0045]

[0046] Figure 1 、 Figure 2 They are the hydrogen spectrum (DMSO-d6) and infrared spectrum (KBr) diagrams of DHTAP. Among them, 9.72 (s), 7.65 (dd), 7.43 (dd), 6.60 (dd), 6.49 (dd), 6.33 (s) are the characteristic hydrogen positions on the nuclear magnetic resonance spectrum, 1620 cm -1 、1584 cm -1 、1505 cm -1 、1479 cm -1 、1449 cm -1 、1315 cm -1They are the vibration peaks of the characteristic functional groups in the DHTAP molecule, which proves the successful synthesis of DHTAP.

[0047] Figure 3 It is the X-ray diffraction pattern of DHTAP, which proves that the material has good crystallinity.

[0048] Example 2:

[0049] Application of the black solid 5,14-dihydro-5,7,12,14-tetraazapentacene (DHTAP) prepared in Example 1 in a metal ion battery. The specific steps are as follows:

[0050] Step 1: Cut a 2×2 cm 2 carbon cloth and ultrasonically clean it with acetone, ethanol, and ultrapure water for 30 minutes each to remove surface impurities. Dry it in a blast drying oven at 60 °C for 24 hours. Take a certain amount of concentrated sulfuric acid and concentrated nitric acid, mix them evenly, and pretreat the carbon cloth. The volume ratio of the two is 1:1. Conduct a hydrothermal reaction at 80 °C for 4 hours. After the reaction ends and the reaction kettle cools to room temperature, take out the treated carbon cloth, repeatedly rinse it with ultrapure water to remove the residual concentrated acid on the carbon cloth, and then dry it in a 60 °C blast drying oven for 24 hours.

[0051] Step 2: On the basis of sufficient stirring, dissolve the DHTAP solid in a 5M hydrochloric acid aqueous solution, add the carbon cloth pretreated in Step 1, and then adjust the pH of the system with a 5M sodium hydroxide aqueous solution. The dropping rate of sodium hydroxide is controlled at 0.02 ml - 0.03 ml per minute until the pH of the system is 10 - 14. After standing for 2 hours, take out the carbon cloth composite electrode, wash it 3 times with deionized water, dry it in a vacuum at 100 °C for 48 hours, and then cut and prepare the positive electrode sheet.

[0052] Step 3: Use the carbon cloth dyed with DHTAP in Step 2 as the positive electrode sheet, use a lithium metal sheet as the counter electrode to assemble a button battery. The electrolyte used is a 1.0M organic electrolyte (the lithium salt is lithium hexafluorophosphate, and the solvent is a mixed solution of ethylene carbonate and diethyl carbonate with a volume ratio of 1:1). The polypropylene membrane is used as the separator, and a CR2032 type stainless steel is used as the battery shell to assemble a button battery, and test its battery performance.

[0053] Step 4: As a comparative experiment, use the existing coating process to prepare a traditional DHTAP electrode sheet. The process is as follows: Mix DHTAP, Ketjen black, and polyvinylidene fluoride (PVDF) in a mass ratio of 60:30:10 and mix them evenly with a small amount of N-methyl-2-pyrrolidone (NMP). Grind them evenly in an agate mortar to form a well-dispersed slurry, and then evenly coat it on an aluminum foil current collector. Dry it in a vacuum at 100 °C for 24 hours to make a working electrode, and then use the same battery assembly process as in Step 3 to test the battery performance.

[0054] The application performance of a carbon cloth electrode after DHTAP staining in a lithium-ion battery is as Figures 4 - 9 shown.

[0055] Figure 4 The scanning electron microscope of the carbon cloth after DHTAP staining prepared in Example 2. It can be seen from the picture that the DHTAP precipitated from the alkaline solution is evenly deposited on the surface of the carbon fiber.

[0056] Figure 5 The charge-discharge curve of the battery assembled based on the DHTAP-stained carbon cloth electrode. It can be seen from the figure that the discharge specific capacity of the composite electrode is 128 mAh / g at a current density of 0.05 A / g, showing good reaction reversibility.

[0057] Figure 6 The cyclic voltammogram curve of the battery assembled based on the DHTAP-stained carbon cloth electrode. It can be known from the figure that there are two pairs of reversible oxidation-reduction peaks for DHTAP.

[0058] Figure 7 and Figure 8 The performance comparison between the battery assembled based on the DHTAP-stained carbon cloth electrode and the DHTAP battery prepared by the traditional coating process. From the comparison of the charge-discharge curves ( Figure 7 ), it can be known that the composite electrode sheet prepared by dyeing and immobilization shows a higher voltage working range, and its battery cycle stability ( Figure 8 ) has been greatly improved, while the DHTAP electrode prepared by the traditional coating process will experience rapid capacity decay.

[0059] Figure 9 The rate performance comparison between the DHTAP-stained carbon cloth prepared in Example 2 and the DHTAP battery prepared by the traditional coating process. Thanks to the effective combination of DHTAP and the carbon substrate, the conductivity of the electrode is improved, resulting in an improvement in the rate performance of the battery.

[0060] The above are only the embodiments of the present invention, and common general technical knowledge such as specific technical solutions or characteristics in the solutions is not described in detail here. It should be noted that for those skilled in the art, without departing from the technical solution of the present invention, several deformations and improvements can still be made, and these should also be regarded as the protection scope of the present invention, and these will not affect the implementation effect of the present invention and the practicality of the patent. The protection scope required by this application should be based on the content of its claims, and the specific implementation manners in the specification can be used to interpret the content of the claims.

[0061] Example 3:

[0062] Under argon protection, 0.6 g of 2,5-dihydroxy-1,4-benzoquinone and 0.8 g of 4,5-dichloro-o-phenylenediamine were successively added to a round-bottom flask. Using 50 mL of ethanol as a solvent, the reaction was carried out at 100 °C with continuous stirring for 24 h. After cooling to room temperature, the solid was collected by suction filtration and washed three times with acetone and methanol respectively. Finally, it was vacuum dried at 100 °C for 24 h to obtain 2,3-dichloro-7,8-dihydrophenazine.

[0063] Then, 0.15 g of 2,3-dichloro-7,8-dihydrophenazine and 1.0 g of 4,5-dichloro-o-phenylenediamine were weighed and 0.5 mL of p-toluenesulfonic acid was added. Using 50 mL of ethylene glycol monomethyl ether as a solvent, the reaction was carried out at 120 °C with continuous stirring for 48 h. After the reaction was completed, it was cooled to room temperature, and the black solid was collected by suction filtration and washed three times with dichloromethane and methanol respectively. Finally, it was vacuum dried at 120 °C for 36 h to obtain a black solid. The synthetic reaction equation is as follows:

[0064]

[0065] Figure 10 is the Fourier transform infrared spectrum of DHTAP-4Cl. It can be seen from the infrared spectrum that 1615 cm -1 , 1562 cm -1 , 1502 cm -1 , 1467 cm -1 , 1451 cm -1 , 1305 cm -1 are the vibration peaks of the characteristic functional groups in the DHTAP-4Cl molecule, proving the successful synthesis of the target product.

[0066] Figure 11 is the charge-discharge curve of the battery assembled based on the DHTAP-4Cl electrode (current density is 0.1 A / g). It can be seen from the figure that the discharge specific capacity of the electrode in the stable state can reach 143 mAh / g at a current density of 0.1 A / g, showing good reaction reversibility.

[0067] Figure 12 is the cycle life of the battery assembled based on the DHTAP-4Cl electrode (current density is 0.05 A / g). The composite electrode sheet obtained based on the preparation process described in Example 2 shows excellent cycle life and can achieve 2000 charge-discharge processes reversibly and stably.

Claims

1. Application of a tetraazapentacene derivative as an electrode material in a metal ion battery, characterized in that, The described metal-ion battery includes a perylene tetrazine composite positive electrode, and further includes a negative electrode material, a separator, and an electrolyte solution; Among them, the perylene tetrazine derivative has the following structure: Among them, the R1-R4 groups can each independently be selected from hydrogen or a halogen; The preparation steps of the perylene tetrazine composite positive electrode are as follows: Step (1): Cut a piece of carbon cloth, ultrasonically clean it to remove surface impurities. Take a certain amount of concentrated sulfuric acid and concentrated nitric acid, mix them evenly, and perform pretreatment on the carbon cloth. Conduct a hydrothermal reaction at 80-120°C for 4-8 hours. After the reaction ends, repeatedly rinse to remove the residual concentrated acid on the carbon cloth; Step (2): Dissolve the perylene tetrazine derivative solid in an acidic aqueous solution, add the carbon cloth treated in step (1), stir well, then let it stand for 2-4 hours. Then adjust the pH to alkaline with a strong base solution, and a solid will precipitate and adhere to the surface of the carbon fiber. Take out the carbon cloth composite electrode, wash it several times with deionized water, vacuum dry it at 100-120°C for 36-48 hours, and then cut it to prepare the positive electrode sheet.

2. The application according to claim 1, characterized in that In step (2), The acidic aqueous solution is one of formic acid, acetic acid, and hydrochloric acid, with a concentration of 3-5M; The strong base solution is one of sodium hydroxide solution or potassium hydroxide solution, with a concentration of 3-5M; the dropping rate of the strong base solution is controlled at 0.02 mL - 0.03 mL per minute until the pH of the system is 10-14.

3. The application according to claim 1, characterized in that, The described metal-ion battery includes a perylene tetrazine composite positive electrode, and further includes the negative electrode material, a separator, and an electrolyte solution; The negative electrode material includes metallic lithium or metallic sodium; The separator is a glass fiber membrane or a PP separator; The electrolyte solution is lithium hexafluorophosphate or sodium hexafluorophosphate dissolved in one or a mixture of two or more of the ester solvents such as ethylene carbonate, propylene carbonate, dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, and fluoroethylene carbonate.

4. The application according to claim 1, characterized in that, The preparation steps of the perylene tetrazine derivative are as follows: (1) Under the protection of an inert gas, add 2,5-dihydroxy-1,4-benzoquinone and o-phenylenediamine derivative A to a reactor, dissolve them in an organic or aqueous solvent, and keep the reaction mixture stirred at a reflux state at a certain temperature to obtain 2,3-(R1, R2)-7,8-dihydrophenazine; Among them, the structure of the o-phenylenediamine derivative A is as follows: The R1 and R2 groups can each independently be selected from hydrogen or halogen; (2) Dissolve the 2,3-(R1, R2)-7,8-dihydrophenazine prepared in step (1) and o-phenylenediamine derivative B in an organic solvent, and keep the reaction mixture stirred at a reflux state at a certain temperature; after the reaction ends, cool the reaction solution to room temperature, filter by suction to collect the solid, wash it several times with acetone and ethanol respectively, and finally vacuum dry it at 100-120°C for 24-30 hours to obtain a black solid; Among them, the structure of the o-phenylenediamine derivative B is as follows: The R3 and R4 groups can each independently be selected from hydrogen or a halogen; In step (1), the molar ratio of o-phenylenediamine derivative A to 2,5-dihydroxy-1,4-benzoquinone is 1:1; the reflux temperature is 100°C - 120°C, and the reaction time is 24 hours; In step (2), the molar ratio of o-phenylenediamine derivative B to 2,3-(R1, R2)-7,8-dihydrophenazine is 5-6:1; the reflux temperature is 100°C - 120°C, and the reaction time is 24-36 hours; The organic solvent is one of ethanol and ethylene glycol monomethyl ether, and the inert gas is one of nitrogen and argon.

Images