CN114300681A - A kind of graphene composite polyimide electrode material and preparation method thereof - Google Patents

Abstract

The invention relates to a lithium ion battery electrode material and a preparation method thereof. The preparation process mainly comprises the steps of dissolving melamine and 1,4,5, 8-naphthalene tetracarboxylic anhydride in a propionic anhydride solution, preparing polyimide through hydrothermal reaction, dispersing the polyimide and graphite oxide in a DMF solution, obtaining a graphene composite polyimide material through heating reaction, mixing the graphene composite polyimide material with acetylene black and PVDF, coating the mixture on a copper foil, and drying to obtain the graphene composite polyimide electrode. The polyimide and graphene composite polyimide electrode material obtained by the invention has the advantages of stable structure, stable chemical property, excellent electrochemical performance, good cycle performance, high specific mass capacity and the like, has great application potential in a supercapacitor electrode material, is simple in preparation method, and has the advantages of strong controllability, no additional auxiliary agent, high efficiency and the like.

Description

A kind of graphene composite polyimide electrode material and preparation method thereof

technical field

The invention belongs to the technical field of new energy electronic materials, and relates to a graphene composite polyimide electrode material and a preparation method thereof.

Background technique

As the most promising alternative to traditional fossil energy, rechargeable lithium-ion batteries dominate applications in plug-in hybrid vehicles, electric vehicles, and various portable electronic devices. Outstanding performance in efficiency and cycle performance plays an irreplaceable role in electrical energy conversion and storage. However, traditional inorganic electrodes such as LiCoO ₂ , LiMn ₂ O ₄ , and LiFePO ₄ suffer from poor safety and poor sustainability, which limit their development in Li-ion batteries. Polyimide is a typical organic carbonyl compound with high theoretical capacity. In addition to high capacity and high energy density, polyimide also has other advantages that inorganic cathode materials do not have. First, their excellent mechanical strength, flexibility, and thermal stability make electrode design more flexible and safer. Second, they are low in synthesis cost and low in recycling cost. However, there is a general problem with polymers, which have poor electrical conductivity. People usually add conductive additives to increase their conductivity. Conductive additives such as carbon, metals, and conductive polymers have been shown to improve rate performance. So far, the main routes for adding conductive additives include coatings, fillers, composites, and matrix frameworks. Among them, conductive carbon fillers such as carbon nanotubes and graphene are widely used as conductive additives for organic electrodes due to their excellent conductivity. Cyclic electrode material.

SUMMARY OF THE INVENTION

In view of the deficiencies of the prior art, the present invention provides a lithium ion battery electrode material with simple process, high efficiency and good electrochemical stability and a preparation method thereof.

The technical scheme of the present invention is as follows:

A lithium ion battery electrode material, the electrode material is compounded by polyimide supported on the surface of graphene.

According to the present invention, a method for preparing a graphene composite polyimide electrode material includes the following steps:

(1) Disperse melamine monomer and 1,4,5,8-naphthalene tetracarboxylic anhydride monomer in propionic anhydride solution;

(2) placing the dispersion of step (1) in a hydrothermal reactor, and placing it in an oven for heating reaction;

(3) the reaction product of step (3) is centrifuged alternately with hot water and ethanol, and the precipitate is taken and placed in an oven to dry to obtain polyimide;

(4) dispersing the polyimide and graphene oxide obtained in step (3) in a DMF solution, adding a small amount of sulfuric acid, and heating and stirring for reaction;

(5) mixing and centrifuging the reaction product of step (4) with ethanol and water, taking the precipitate and placing it in an oven to dry to obtain a graphene composite polyimide material;

(6) Dissolve graphene composite polyimide, acetylene black and PVDF into N-methylpyrrolidone solution, stir evenly, apply the homogenate to copper foil with a scraper, and dry it in a vacuum oven to prepare A positive electrode sheet for lithium-ion batteries.

According to the present invention, preferably, in step (1), the melamine monomer and the 1,4,5,8-naphthalenetetracarboxylic anhydride monomer are dispersed in the propionic anhydride solution: first, the melamine monomer is dissolved in the propionic anhydride, and the ultrasonic Disperse uniformly, then add 1,4,5,8-naphthalene tetracarboxylic anhydride to disperse uniformly by ultrasonic

According to the present invention, preferably, the molar ratio of melamine and 1,4,5,8-naphthalenetetracarboxylic anhydride in step (1) is 2:3, wherein melamine is 3.33mmol (0.4204g), 1,4,5, 8-Naphthalenetetracarboxylic anhydride is 5.0 mmol (1.3409 g);

According to the present invention, preferably, in step (1), the amount of propionic anhydride used is 20 mL, and the capacity of the hydrothermal reactor used is 50 mL.

According to the present invention, preferably, the reaction temperature in step (2) is 150°C, and the reaction time is 15h.

According to the present invention, preferably, in step (3), the product is centrifuged with hot water and ethanol until colorless, and after centrifugation, the product is placed in an oven at 60° C. for 12 hours.

According to the present invention, preferably, the graphene oxide quality index in step (4) is: purity>98.0 wt%, ash <0.1 wt%, specific surface area 200-600m ² /g, average number of layers 3-10 layers, graphene The lamella size is 0.1-3 μm, the oxygen content is <0.3 wt%, and the sulfur content is <0.2 wt%.

According to the present invention, preferably, in step (4), the amount of DMF is 30 mL, the amount of graphite oxide is 0.01 g, the amount of polyimide is 0.1 g, and the amount of sulfuric acid is 3 mL.

According to the present invention, preferably, in step (5), the product is alternately centrifuged with ethanol and water until it is colorless, and after centrifugation, the product is placed in an oven at 60° C. for 12 hours.

According to the present invention, preferably, in step (6), the graphene composite polyimide, acetylene black and PVDF are dissolved in the N-methylpyrrolidone solution according to the mass ratio of 6:3:1, stirred evenly, and the homogenate is mixed with A 200 μm doctor blade was applied to the copper foil, the temperature of the vacuum oven was 100 °C, and the baking time was 12 h.

The technical advantages of the present invention are as follows:

(1) The preparation process of the present invention is simple, and has the advantages of strong controllability, no external additives and high efficiency;

(2) The graphene composite polyimide electrode material prepared by the present invention has the advantages of stable structure, stable chemical properties, excellent electrochemical performance, good cycle performance and high mass specific capacity, and is very suitable for use as a positive electrode material in the field of lithium ion batteries .

Description of drawings

Fig. 1 is the infrared spectrogram of the polyimide obtained in Example 1 of the present invention;

Fig. 2 is the cycle specific capacity diagram of the polyimide electrode material and the graphene composite polyimide electrode material obtained in Example 1 and Example 2 of the present invention;

Fig. 3 is the scanning electron microscope picture of the polyimide obtained in the embodiment of the present invention 1;

4 is a scanning electron microscope image of the graphene composite polyimide prepared in Example 2 of the present invention.

Detailed ways

The present invention is further described below with reference to specific embodiments and accompanying drawings, but is not limited thereto.

Meanwhile, the experimental methods described in the following examples are conventional methods unless otherwise specified; the reagents and materials can be obtained from commercial sources unless otherwise specified.

Example 1: 3.33 mmol (0.4204 g) of melamine and 5.0 mmol (1.3409 g) of 1,4,5,8-naphthalene tetracarboxylic anhydride were taken respectively according to the molar ratio of 2:3, followed by melamine and 1,4,5,8 - Naphthalene tetracarboxylic anhydride was dissolved in 20 mL of propionic anhydride, and ultrasonically dispersed uniformly. The above dispersion was put into a 50 mL hydrothermal reaction kettle, and the reaction kettle was placed in an oven at 150 °C for 15 h. After the reaction, the product was heated The polyimide was obtained by alternate centrifugation of water and ethanol until colorless.

Polyimide, acetylene black and PVDF were dissolved in N-methylpyrrolidone solution according to the mass ratio of 6:3:1, stirred evenly, and the homogenate was coated on the copper foil with a 200 μm scraper, and the temperature of the vacuum oven was 100 ℃ , the baking time is 12h, and the polyimide electrode material is obtained after drying.

The electrode material is subjected to the charge-discharge cycle test, and the obtained polyimide electrode material can be stably charged and discharged for more than 6000 cycles at a current density of 1mA/g, and its mass specific capacity is about 122.9mAh/g. Good, but lower mass than capacity.

Example 2: 3.33 mmol (0.4204 g) of melamine and 5.0 mmol (1.3409 g) of 1,4,5,8-naphthalene tetracarboxylic anhydride were taken respectively according to the molar ratio of 2:3, followed by melamine and 1,4,5,8 - Naphthalene tetracarboxylic anhydride was dissolved in 20 mL of propionic anhydride, and ultrasonically dispersed uniformly. The above dispersion was put into a 50 mL hydrothermal reaction kettle, and the reaction kettle was placed in an oven at 150 °C for 15 h. After the reaction, the product was heated The polyimide was obtained by alternate centrifugation of water and ethanol until colorless.

According to the mass ratio of 10:1, take 0.1 g of polyimide and 0.01 g of graphite oxide, dissolve them in 30 mL of DMF solution, and ultrasonically disperse them evenly, then add 3 mL of sulfuric acid, and stir the above solution at 110 °C for 12 h. Alternate centrifugation with ethanol to neutrality to obtain graphene composite polyimide material

Graphene composite polyimide, acetylene black and PVDF were dissolved in N-methylpyrrolidone solution according to the mass ratio of 6:3:1, stirred evenly, and the homogenate was coated on the copper foil with a 200 μm scraper, and the temperature of the vacuum oven was The temperature is 100° C., the baking time is 12 h, and the graphene composite polyimide electrode material is obtained after drying.

The electrode material is subjected to the charge-discharge cycle test, and the obtained graphene composite polyimide electrode material can be stably charged and discharged for more than 2300 cycles at a current density of 1mA/g, and its mass specific capacity is 551.9mAh/g on average. Good cyclability and high mass specific capacity.

Claims (4)

1. A lithium ion battery positive electrode material, characterized in that the electrode material is a polyimide electrode material, which is formed by polymerization of melamine and 1,4,5,8-naphthalene tetracarboxylic anhydride. 2. A lithium ion battery positive electrode material, characterized in that the electrode material is a graphene composite polyimide material, which is formed by the composite of the polyimide according to claim 1 and graphene. 3. a preparation method of the described lithium ion battery electrode material of claim 1, comprises the steps as follows: (1) According to the molar ratio of 2:3, take 3.33 mmol (0.4204 g) of melamine and 5.0 mmol (1.3409 g) of 1,4,5,8-naphthalene tetracarboxylic anhydride, respectively, melamine and 1,4,5,8- Naphthalene tetracarboxylic anhydride was dissolved in 20mL propionic anhydride, and ultrasonically dispersed uniformly; (2) Put the above dispersion liquid into a 50 mL hydrothermal reaction kettle, put the reaction kettle into an oven at 150 °C for 15 hours, and after the reaction is completed, the product is alternately centrifuged with hot water and ethanol until it is colorless to obtain polyimide amine; (3) Polyimide, acetylene black and PVDF were dissolved in N-methylpyrrolidone solution according to the mass ratio of 6:3:1, stirred evenly, and the homogenate was coated on the copper foil with a 200 μm scraper, and the temperature of the vacuum oven was The temperature was 100° C., the baking time was 12 h, and the polyimide electrode material was obtained after drying. 4. a preparation method of the described lithium ion battery electrode material of claim 2, comprises the steps as follows: (1) According to the mass ratio of 10:1, take 0.1 g of polyimide obtained in claim 1 and 0.01 g of graphite oxide, dissolve them in 30 mL of DMF solution, and ultrasonically disperse them evenly, and then add 3 mL of sulfuric acid; (2) The above solution was stirred and reacted at 110 °C for 12 h, and the product was alternately centrifuged with water and ethanol until neutral, to obtain a graphene composite polyimide material; (3) Graphene composite polyimide, acetylene black and PVDF were dissolved in N-methylpyrrolidone solution according to the mass ratio of 6:3:1, stirred evenly, and the homogenate was coated on the copper foil with a 200 μm scraper, The temperature of the vacuum oven is 100° C. and the baking time is 12 h, and the graphene composite polyimide electrode material is obtained after drying.

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