Preparation method and application of polymer nanosheet

Abstract

The invention provides a preparation method and application of a polymer nanosheet. The preparation method provided by the invention comprises the following steps: carrying out solvothermal reaction on 2, 6-diamino-anthraquinone and terephthalaldehyde to prepare poly (anthraquinone-phenyleneimine) with a conjugated structure, then carrying out protonation reaction on methanesulfonic acid and an imine structure in the polymer, and finally obtaining the lamellar conjugated polymer through an ultrasonic stripping method. The preparation method is simple, and the obtained polymer nanosheet shows excellent electrochemical performance when applied to a sodium ion battery.

Description

Technical Field

[0001] This invention relates to the field of sodium-ion battery technology, and in particular to a method for preparing polymer nanosheets and their application. Technical Background

[0002] Organic electrodes can be directly obtained from many natural substances, making them less expensive and more environmentally friendly than inorganic electrode materials. However, lower molecular weight organic small molecule electrode materials are easily dissolved in electrolytes, resulting in poor cycle stability, which greatly affects their practical application in sodium-ion batteries. Therefore, improving the performance and stability of organic electrodes in sodium-ion batteries remains a challenge.

[0003] Constructing conjugated structures and increasing the degree of polymerization of organic electrode materials can effectively suppress the dissolution of active components. Furthermore, the formation of π-conjugated structures between organic electrode materials can significantly improve the low intrinsic conductivity of the material, promoting charge transfer and sodium ion diffusion. N and O atoms in organic electrode materials form intermolecular hydrogen bonds, creating a stable electrode structure that contributes to long cycle life. However, the tight stacking structure of the polymer itself prevents the active groups from being adequately exposed, resulting in low utilization of active sites and limiting capacity in practical processes. Therefore, how to expose more redox active sites in the prepared conjugated polymers to achieve high utilization efficiency and obtain high-capacity, long-life sodium ion storage performance is a bottleneck problem that urgently needs to be solved. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing polymer nanosheets to expose more redox active sites in conjugated polymers, thereby achieving high utilization efficiency and obtaining high-capacity, long-lifetime sodium ion storage performance. This polymer preparation method is simple, exhibits excellent intrinsic physicochemical and electrochemical properties, and shows promising application prospects.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution: A method for preparing polymer nanosheets, characterized by comprising the following steps: 2,6-Diaminoanthraquinone and terephthalaldehyde were dispersed and dissolved in N,N-dimethylformamide (DMF), and then subjected to a solvothermal Schiff base reaction to obtain the crude product.

[0006] Preferably, the 2,6-diaminoanthraquinone is dissolved in DMF at a concentration of 50-100 mg / mL; the terephthalaldehyde is dissolved in DMF at a concentration of 60-100 mg / mL, and then the terephthalaldehyde DMF solution is slowly added to the 2,6-diaminoanthraquinone DMF solution under stirring. In the total dosage, the molar ratio of amino small molecules to aldehyde small molecules is 1:1-1.2.

[0007] Preferably, solvent reflux is required in the solvothermal Schiff base reaction.

[0008] Preferably, the reaction system is placed in an inert gas atmosphere; the reaction temperature of the solvothermal Schiff base reaction is set to 110-150 °C, the stirring speed is 200-400 r / min, and the time is 6-24 h.

[0009] Preferably, the crude product is washed 2-6 times sequentially with hot DMF, ethanol, and dioxane to remove small molecules with low degree of polymerization, until the washing solution becomes clear and has no obvious color; then the reaction product is dried.

[0010] Preferably, centrifugation is used to remove the liquid first, followed by drying, with a centrifugation speed of 1000-3000 r / min.

[0011] The polymers prepared by any of the methods described above in this invention are blocky structures formed by layered stacking through hydrogen bonding and van der Waals forces. Further: The dried reaction product, i.e. the polymer mentioned above, was dispersed in a methanesulfonic acid solution at a concentration of 0.5-2 mg / ml to obtain a suspension. The suspension was broken down and ultrasonically dispersed in an ice-water bath; then deionized water (DI) was added for multiple washings and centrifugation until the pH was neutral to remove residual methanesulfonic acid; finally, layered conjugated polymer nanosheets were obtained.

[0012] The present invention also provides the application of the nanosheets described above in sodium-ion batteries, which enables the low-cost preparation of high-capacity, long-life, high-performance sodium-ion batteries. Attached Figure Description

[0013] Figure 1 This is a SEM image of the microstructure of the crude product provided in Example 1 of the present invention.

[0014] Figure 2 The image shown is a SEM image of the microstructure of the conjugated polymer nanosheets provided in Example 1 of this invention, illustrating the regular sheet morphology.

[0015] Figure 3 The GCD cycle curve of the sodium-ion battery described in Example 1 at a current of 0.1 A g⁻¹ is shown. Specific implementation methods

[0016] This invention provides a method for preparing polymer nanosheets, comprising the following steps: 2,6-Diaminoanthraquinone and terephthalaldehyde were dispersed and dissolved in N,N-dimethylformamide (DMF), and then subjected to a solvothermal Schiff base reaction to obtain the crude product.

[0017] In this invention, unless otherwise specified, all raw materials used in the preparation are commercially available products well known to those skilled in the art.

[0018] In this invention, the 2,6-diaminoanthraquinone is dissolved in DMF, preferably at a concentration of 50-100 mg / mL, more preferably 60-90 mg / mL, and most preferably 70-90 mg / mL.

[0019] In this invention, the terephthalaldehyde is dissolved in DMF, and the concentration is preferably 50-100 mg / mL, more preferably 60-95 mg / mL, and most preferably 75-85 mg / mL.

[0020] In this invention, the molar ratio of amino small molecules to aldehyde small molecules in the total dosage is preferably 1:1.2, more preferably 1:1.1, and most preferably 1:1-1.05.

[0021] In the above-described reaction of the present invention, the reaction temperature is preferably 110-150°C, more preferably 110-140°C, and most preferably 120-140°C.

[0022] In the above reaction of the present invention, the stirring speed is preferably 200-400 r / min, more preferably 200-300 r / min.

[0023] In the above-described reaction of the present invention, the reaction time is preferably 6-24 h, more preferably 10-20 h, and most preferably 12-16 h.

[0024] In this invention, the reaction product obtained by the preparation method is washed 2-6 times with hot DMF, ethanol and dioxane until the washing solution becomes clear and has no obvious color, and then the reaction product is dried.

[0025] In this invention, the drying conditions are preferably drying in a vacuum oven at 120 °C for 12-48 h, more preferably 10-24 h, and most preferably 12-16 h.

[0026] In this invention, further, The dried reaction product is dispersed in a methanesulfonic acid solution at a concentration of 0.5-2 mg / ml to obtain a suspension; the preferred concentration is 0.5-2 mg / ml, the more preferred concentration is 1-2 mg / ml, and the most preferred concentration is 1-1.5 mg / ml. The suspension was broken down and ultrasonically dispersed in an ice-water bath; then deionized water (DI) was added for multiple washings and centrifugation until the pH was neutral to remove residual methanesulfonic acid; finally, layered conjugated polymer nanosheets were obtained.

[0027] In this invention, the centrifugation speed for the above-mentioned multiple washing and centrifugation is preferably 2000~10000 r / min, more preferably 2000~5000 r / min, and most preferably 3000~4000 r / min.

[0028] In this invention, the nanosheet product is obtained by washing and centrifuging multiple times and then drying in an oven. The drying time is preferably 12-48h, more preferably 12-24h, and most preferably 12-16h.

[0029] The present invention will be further illustrated below with specific examples. These embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims. Example

[0030] 1.9 g of diaminoanthraquinone was placed in a reaction system under nitrogen atmosphere protection, and 25 mL of DMF was added. The mixture was stirred for 30 min. 15 mL of DMF solution containing 1.2 g of terephthalaldehyde was added dropwise to the above solution, and stirring continued for 30 min. The molar ratio of diaminoanthraquinone to terephthalaldehyde was 1:1.05. The reaction was gradually heated to 120 °C, and the stirring speed was 300 r / min. After reacting for 12 h under the above experimental conditions, the crude product was separated by filtration. The obtained reaction product was washed 2-6 times successively with hot DMF, ethanol, and dioxane until the washing solution became clear and colorless. It was then dried in a vacuum drying oven at 120 °C for 12 h. The SEM image of the microstructure of the crude product is attached. Figure 1 As shown.

[0031] 100 mg of the obtained product was dispersed in 100 mL of methanesulfonic acid and ultrasonically disrupted for 60 min in an ice-water bath. Then, 500 mL of deionized water was added to the suspension, and the mixture was washed and centrifuged until neutral (centrifugation speed was set to 4000 r / min). The separated product was dried in a vacuum oven for 24 h to obtain the target polymer nanosheets. SEM images of the microstructure of the conjugated polymer nanosheets are attached. Figure 2 As shown, the illustration depicts a regular lamellar morphology.

[0032] Weigh 30 mg of the polymer nanosheets prepared in the experiment, 15 mg of carbon black, and 5 mg of polyvinylidene fluoride. Add 3 mL of N-methylpyrrolidone, mix and stir, and grind for 30 min. Coat the resulting slurry onto copper foil with a thickness of 20 μm. Place the slurry in a vacuum drying oven at 120 ℃ for 12 h. Cut electrode sheets and assemble a sodium-ion battery using a 1 M NaCF3SO3 diethylene glycol dimethyl ether electrolyte. Test the battery in the Xinwei CT-4008Tn battery test channel with a test current of 1 A g⁻¹. The voltage range is 0.01-3 V. The GCD cycle curve of the sodium-ion battery at a current of 0.1 A g⁻¹ is attached. Figure 3 As shown, the reversible capacity remains at ~300 mA h g⁻¹ after 100 cycles at a current density of 1 A g⁻¹. Example

[0033] 1.9 g of diaminoanthraquinone was placed in a reaction system under nitrogen atmosphere, and 25 mL of DMF was added. The mixture was stirred for 30 min. 15 mL of DMF solution containing 1.88 g of biphenyl dicarboxaldehyde was added dropwise to the above solution, and stirring was continued for 30 min. The molar ratio of diaminoanthraquinone to biphenyl dicarboxaldehyde was 1:1.05. The reaction was gradually heated to 120 °C, and the stirring speed was 300 r / min. After reacting for 12 h under the above experimental conditions, the crude product was separated by vacuum filtration. The obtained reaction product was washed 2-6 times successively with hot DMF, ethanol, and dioxane until the washing solution became clear and colorless. It was then dried in a vacuum drying oven at 120 °C for 12 h.

[0034] 100 mg of the product was dispersed in 100 mL of methanesulfonic acid and ultrasonically disrupted in an ice-water bath for 60 min. Then, 500 mL of deionized water was added to the suspension, and the mixture was washed and centrifuged until neutral. The centrifugation speed was set to 4000 r / min. The separated product was dried in a vacuum oven for 24 h to obtain the target polymer nanosheets.

[0035] Weigh 30 mg of the polymer nanosheets prepared in the experiment, 15 mg of carbon black, and 5 mg of polyvinylidene fluoride. Add 3 mL of N-methylpyrrolidone, mix and stir, and grind for 30 min. Coat the resulting slurry onto copper foil to a thickness of 20 μm. Place the slurry in a vacuum drying oven at 120 ℃ for 12 h. Cut electrode sheets and assemble a sodium-ion battery using 1 M NaCF3SO3 diethylene glycol dimethyl ether electrolyte. Test the battery in the Xinwei CT-4008Tn battery test channel with a test current of 1 A g⁻¹ and a voltage range of 0.01–3 V. Example

[0036] 1.9 g of diaminoanthraquinone was placed in a reaction system under nitrogen atmosphere protection, and 25 mL of DMF was added. The mixture was stirred for 30 min. 15 mL of DMF solution containing 1.45 g of trimesin was added dropwise to the above solution, and stirring continued for 30 min. The molar ratio of diaminoanthraquinone to trimesin was 1:1.05. The reaction was gradually heated to 120 °C, and the stirring speed was 300 r / min. After reacting for 12 h under the above experimental conditions, the crude product was separated by vacuum filtration. The obtained reaction product was washed 2-6 times successively with hot DMF, ethanol, and dioxane until the washing solution became clear and colorless. It was then dried in a vacuum drying oven at 120 °C for 12 h.

[0037] 100 mg of the product was dispersed in 100 mL of methanesulfonic acid and ultrasonically disrupted in an ice-water bath for 60 min. Then, 500 mL of deionized water was added to the suspension, and the mixture was washed and centrifuged until neutral. The centrifugation speed was set to 4000 r / min. The separated product was dried in a vacuum oven for 24 h to obtain the target polymer nanosheets.

[0038] Weigh 30 mg of the polymer nanosheets prepared in the experiment, 15 mg of carbon black, and 5 mg of polyvinylidene fluoride. Add 3 mL of N-methylpyrrolidone, mix and stir, and grind for 30 min. Coat the resulting slurry onto copper foil to a thickness of 20 μm. Place the slurry in a vacuum drying oven at 120 ℃ for 12 h. Cut electrode sheets and assemble a sodium-ion battery using 1 M NaCF3SO3 diethylene glycol dimethyl ether electrolyte. Test the battery in the Xinwei CT-4008Tn battery test channel with a test current of 1 A g⁻¹ and a voltage range of 0.01–3 V. Example

[0039] 0.86 g of p-phenylenediamine was placed in a reaction system under a nitrogen atmosphere, and 25 mL of DMF was added. The mixture was stirred for 30 min. 15 mL of DMF solution containing 1.45 g of trimesin was added dropwise to the above solution, and stirring continued for 30 min. The molar ratio of diaminoanthraquinone to trimesin was 1:1.05. The reaction was gradually heated to 120 °C, and the stirring speed was 300 r / min. After reacting for 12 h under the above experimental conditions, the crude product was separated by vacuum filtration. The obtained reaction product was washed 2-6 times successively with hot DMF, ethanol, and dioxane until the washing solution became clear and colorless. It was then dried in a vacuum drying oven at 120 °C for 12 h.

[0040] 100 mg of the product was dispersed in 100 mL of methanesulfonic acid and ultrasonically disrupted in an ice-water bath for 60 min. Then, 500 mL of deionized water was added to the suspension, and the mixture was washed and centrifuged until neutral. The centrifugation speed was set to 4000 r / min. The separated product was dried in a vacuum oven for 24 h to obtain the target polymer nanosheets.

[0041] Weigh 30 mg of the polymer nanosheets prepared in the experiment, 15 mg of carbon black, and 5 mg of polyvinylidene fluoride. Add 3 mL of N-methylpyrrolidone, mix and stir, and grind for 30 min. Coat the resulting slurry onto copper foil to a thickness of 20 μm. Place the slurry in a vacuum drying oven at 120 ℃ for 12 h. Cut electrode sheets and assemble a sodium-ion battery using 1 M NaCF3SO3 diethylene glycol dimethyl ether electrolyte. Test the battery in the Xinwei CT-4008Tn battery test channel with a test current of 1 A g⁻¹ and a voltage range of 0.01–3 V.

[0042] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for preparing polymer nanosheets, characterized in that, Includes the following steps: 2,6-Diaminoanthraquinone and terephthalaldehyde were dispersed and dissolved in N,N-dimethylformamide (DMF), and then subjected to a solvothermal Schiff base reaction to obtain the crude product.

2. The preparation method according to claim 1, characterized in that, The 2,6-diaminoanthraquinone was dissolved in DMF at a concentration of 50-100 mg / mL; the terephthalaldehyde was dissolved in DMF at a concentration of 60-100 mg / mL, and the terephthalaldehyde DMF solution was then slowly added to the 2,6-diaminoanthraquinone DMF solution under stirring. In the total dosage, the molar ratio of amino small molecules to aldehyde small molecules is 1:1-1.

2.

3. The preparation method according to claim 1, characterized in that, In the solvothermal Schiff base reaction, solvent reflux is required.

4. In the preparation method according to claim 1, the characteristic is that... The reaction system is placed under an inert gas atmosphere; the reaction temperature of the solvothermal Schiff base reaction is set to 110-150 ℃, the stirring speed is 200-400 r / min, and the time is 6-24 h.

5. The preparation method according to claim 1, characterized in that, The crude product was washed 2-6 times sequentially with hot DMF, ethanol, and dioxane to remove small molecules with low degree of polymerization. The washing solution was washed until it became clear and colorless. The reaction product was then dried.

6. The preparation method according to claim 5, characterized in that, First, centrifuge to remove the liquid, and then dry it. The centrifugation speed is 1000-3000 r / min.

7. The preparation method according to any one of claims 1-6, characterized in that, The polymer obtained is a blocky structure formed by layered stacking through hydrogen bonding and van der Waals forces.

8. The preparation method according to claim 5, characterized in that, The dried reaction product was dispersed in a methanesulfonic acid solution at a concentration of 0.5-2 mg / ml to obtain a suspension. The suspension was broken down and ultrasonically dispersed in an ice-water bath; then deionized water (DI) was added for multiple washings and centrifugation until the pH was neutral to remove residual methanesulfonic acid; finally, layered conjugated polymer nanosheets were obtained.

9. The conjugated polymer nanosheets prepared by the preparation method according to claim 8 are used in sodium-ion batteries.

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