CN110600277A - Preparation method and application of porous graphene-based composite film material - Google Patents

Abstract

The invention discloses a method for preparing a porous graphene-based composite film material, comprising the following steps: (1) preparation of a porous graphene dispersion; (2) preparation of a carbon nanotube@pseudocapacitive material dispersion; (3) Preparation of composite film material: Mix porous graphene dispersion with carbon nanotube@pseudocapacitive material dispersion, ultrasonic; vacuum filtration, filter cake natural drying, peeling off to obtain porous graphene/carbon nanotube@pseudocapacitive material composite film Material. The porous graphene-based composite film material prepared by the present invention can be directly used as a flexible electrode material without a conductive agent and a binder, and it has excellent rate characteristics, high energy/power density and long cycle life, and the cost of raw materials is low , the process is simple, and the environment is friendly, and it has good application prospects in the field of electrode materials for flexible supercapacitors.

Description

A kind of preparation method and application of porous graphene-based composite film material

technical field

The invention relates to the structural design and preparation of flexible composite electrode materials, and belongs to the fields of material science and electrochemical technology, and more specifically relates to a preparation method and application of a porous graphene-based composite thin film material.

Background technique

With the rapid development of electronic technology, mobile electronic devices are gradually becoming more flexible, thinner and wearable. However, traditional energy storage devices (such as batteries) are rigid products, and when folded or bent, it is easy to cause separation of electrode materials and current collectors, degrade electrochemical performance, and even cause short circuits, posing a huge safety hazard. Therefore, in order to adapt to the development of a new generation of flexible electronic devices, new thin and flexible electrochemical energy storage devices have become a research hotspot today.

Among many energy storage devices, supercapacitors, as a new type of green energy storage device, have the characteristics of high charge and discharge efficiency, long cycle life and high power density, which can make up for the shortage of batteries. However, the current energy density of flexible supercapacitors is still low, and the electrochemical stability of the device during bending and folding is difficult to guarantee, which limits its practical application to a certain extent. Therefore, how to improve the energy density of supercapacitors while maintaining the original high power density and long cycle life is a new challenge in the field of flexible energy storage device research in recent years.

As we all know, the core of a flexible supercapacitor is a flexible electrode sheet with high performance. At present, there are mainly two types of flexible electrode pole pieces: one uses non-conductive flexible substrates such as polymers, paper, and textile fabrics. The substrate skeleton itself hardly contributes to the capacity of the electrode, and its conductivity is poor, which in turn reduces the capacity of supercapacitors. The energy density and fast charge and discharge ability, and there is also the possibility of reaction with the electrolyte; the other uses a conductive flexible matrix such as graphene, and the active material is attached to the structural unit of the flexible matrix skeleton to form a whole flexible electrode, no need to add Any conductive agent and binder has obvious advantages in terms of quality and volume compared with non-conductive flexible substrates, and is the mainstream development direction of high-energy-density flexible energy storage devices in the future.

However, graphene sheets are prone to agglomeration, which affects its application as a substrate for flexible electrodes. Researchers at home and abroad proposed to introduce supports between graphene sheets. For example, YamingWang et al. self-assembled carbon black particles and graphene nanosheets into graphene/carbon black composite film flexible electrode materials (J.Power Sources, 2014, 271,269-277), the carbon black particles play the role of spacer graphene nanosheets, and show excellent rate characteristics; but due to the limitation of the electric double layer energy storage mechanism, the specific capacity of the graphene/carbon black composite film is only 112F g ^-1 . Pooi See Lee et al. introduced pseudocapacitive materials between graphene sheets, which effectively suppressed the agglomeration of graphene and improved the specific capacity of flexible electrode materials (Adv.Mater.,2013,25(20):2809-2815); However, for pseudocapacitive materials, especially metal oxides, the addition of graphene-based flexible electrode materials tends to destroy the conductive network of graphene. In order to solve this problem, Jie Liu et al. introduced third-phase carbon nanotubes into graphene/manganese dioxide powder to improve the conductivity and flexibility of the composite material, and prepared graphene/manganese dioxide/carbon nanotube composite films (Nano Lett.,2012,12(8):4206-4211), the composite film shows a high specific capacity of 372F g ^-1 as a flexible overall electrode material; Transmission and diffusion, and the poor ion transfer ability in the radial direction, resulting in rapid decline in specific capacity under high current charge and discharge conditions, the rate characteristics of electrode materials are poor, and its specific capacity retention rate is only 45%.

Therefore, how to improve the specific capacity of flexible electrode materials and ensure the specific capacity retention rate under the condition of high current charge and discharge has become a technical problem to be solved urgently in this field.

Contents of the invention

In view of this, the present invention uses porous graphene prepared by chemical etching method and carbon nanotube@pseudocapacitive material prepared by hydrothermal method as elementary materials, and constructs a three-dimensional ion diffusion channel, an overall conductive network, Thin film materials with functional integration such as surface modification and high pseudocapacitance.

In order to achieve the above object, the present invention adopts the following technical solutions:

A preparation method of a porous graphene-based composite film material, comprising the steps of:

(1) Preparation of porous graphene dispersion: adopt Hummers method to prepare graphite oxide dispersion, ultrasonically disperse evenly, add potassium permanganate and microwave treatment; add hydrazine hydrate and ammonia water in turn under stirring condition after cooling, and obtain the mixed system water bath Heating; add oxalic acid after the solution is cooled, and stir; suction filter, wash, and use deionized water to prepare the filter cake into a porous graphene dispersion;

(2) Preparation of carbon nanotube@pseudocapacitive material dispersion: carbon nanotubes are ultrasonically dispersed in a solvent, and metal oxides, or metal salts, or metal salts + alkali are added to obtain a hydrothermal treatment system for hydrothermal treatment; cooling After suction filtration, washing, drying, using deionized water to prepare carbon nanotube@pseudocapacitive material dispersion;

(3) Preparation of composite thin film material: Mix porous graphene dispersion with carbon nanotube@pseudocapacitance material dispersion, ultrasonic; vacuum filtration, natural drying of filter cake, exfoliation to obtain porous graphene/carbon nanotube@pseudocapacitance The material is a composite film material.

Using porous graphene prepared by chemical etching method and carbon nanotube@pseudocapacitive material prepared by hydrothermal method as the basic unit to prepare composite thin film material, the pseudocapacitive material is grown in situ on the carbon nanotube to construct a structure with high internal conductivity and high external Pseudocapacitive carbon nanotubes@pseudocapacitive materials, which are supported between graphene layers, can not only inhibit the reunion of graphene sheets but also build ion diffusion channels between layers; porous graphene is the supporting framework of composite thin film materials and The conductive network and the pores on the graphene sheet ensure that the electrolyte ions can diffuse rapidly in the radial direction, and establish a three-dimensional well-developed ion diffusion channel. At the same time, porous graphene can also buffer the volume of the pseudocapacitive material during charge and discharge. swell.

Preferably, in the step (1):

The graphite oxide concentration in the graphite oxide dispersion is 0.2-2.0mg mL ^-1 ;

The mass ratio of potassium permanganate to graphite oxide is 1:1-8:1;

The dosage of hydrazine hydrate is 0.05-5mL/150mL mixed system;

The amount of ammonia water is 0.3-8mL/150mL mixed system.

Preferably, in the step (1):

The microwave treatment time is 5-30min, and the power is 800-1300W;

The heating time in the water bath is 10-60min, and the temperature is 90-100°C;

The dosage of oxalic acid is 2g/150mL mixed system, after adding oxalic acid, stir for at least 12h.

Preferably, in the step (2):

Pseudocapacitive materials include metal oxides or metal hydroxides;

The metal oxide includes manganese dioxide, ferric oxide, tin dioxide or vanadium pentoxide;

The metal hydroxide includes nickel hydroxide.

Preferably, in the step (2):

The concentration of carbon nanotubes in the hydrothermal treatment system is 0.1-0.35 mg mL ^-1 ;

The concentration of metal oxide or metal salt in the hydrothermal treatment system is 5-50 μmol mL ^-1 ;

The hydrothermal treatment temperature is 80-240°C, and the time is 1-12h.

Preferably, in the step (3):

The mass ratio of the porous graphene in the porous graphene dispersion to the carbon nanotube@pseudocapacitive material in the carbon nanotube@pseudocapacitive material dispersion is 1:4-3:1.

Further preferably, the mass ratio of porous graphene to carbon nanotube@pseudocapacitive material is 1:1, 1:2, 1:3, 1:4, 2:1 or 3:1.

A porous graphene-based composite film material prepared by the above preparation method.

Preferably, the unit mass of the composite film material is 0.5-2 mg cm ^-2 .

Application of a porous graphene-based composite film material as an electrode material in a flexible supercapacitor. The specific capacitance at a current density of 1Ag ^-1 can reach 200-900F g ^-1 , the energy density of an asymmetric supercapacitor can reach 20-50Whkg ^-1 , and after 2000-10000 cycles, its service life can reach the initial specific capacity. 60-110%.

It can be seen from the above technical scheme that the porous graphene-based composite film material prepared by the present invention can be directly used as a flexible electrode material without conductive agent and binder, and it has excellent rate characteristics, high energy/power density and long cycle The service life, low cost of raw materials, simple process, and environmental friendliness have good application prospects in the field of electrode materials for flexible supercapacitors.

Description of drawings

Shown in Fig. 1 is the porous graphene/carbon nanotube@MnO that embodiment ₁ obtainsComposite thin film material physical photo;

Fig. 2 shows the porous graphene/carbon nanotube@MnO obtained in embodiment ₁ The SEM figure under different magnifications of the composite thin film material;

Fig. 3 shows the galvanostatic charge-discharge curves of the porous graphene/carbon nanotube@ _MnO composite film material obtained in Example 1 under different current densities;

Fig. 4 shows the specific capacity decay curve of the porous graphene/carbon nanotube@ _MnO composite film material obtained in Example 1 under different current densities;

Fig. 5 shows the porous graphene/carbon nanotube@MnO obtained by embodiment ₁ The cycle life curve of the composite thin film material;

Figure 6 shows that the porous graphene/carbon nanotube @ _MnO2 composite film material obtained in Example 1 is the positive electrode, and the porous graphene/carbon nanotube composite film material is the asymmetric supercapacitor assembled by the negative electrode at different scanning speeds The CV curve under;

Figure 7 shows the power-energy density of the asymmetric supercapacitor assembled by the porous graphene/carbon nanotube @ _MnO2 composite film material obtained in Example 1 as the positive electrode and the porous graphene/carbon nanotube composite film material as the negative electrode picture.

Detailed ways

The following clearly and completely describes the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only some of the embodiments of the present invention, but not all of them. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

Example 1

(1) Preparation of porous graphene dispersion: prepare graphite oxide dispersion by Hummers method, the concentration of graphite oxide in the aqueous dispersion is 0.5 mg mL ^-1 , take 100 mL of graphite oxide dispersion and ultrasonically treat it for 1 h to make it uniform Disperse; add 0.0606g of KMnO ₄ under continuous stirring, and heat with 1000W microwave for 5min; when the temperature drops to room temperature, add 50mL of deionized water, 100μL of hydrazine hydrate and 350μL of ammonia water; Heating in a water bath for 20 min, cooling to room temperature, adding 2 g of oxalic acid and stirring for at least 12 h; suction filtering, washing the final product with deionized water until neutral, and preparing a porous graphene dispersion with a concentration of 0.33 mg mL ^-1 .

(2) Preparation of carbon nanotube @MnO ₂ dispersion: disperse 20 mg of carbon nanotubes in 200 mL of deionized water, add 160 mg of KMnO ₄ , and keep heating in a water bath at 80°C for 2 hours; Wash with deionized water until neutral, and dry in a forced air oven at 80°C for 12 hours; prepare a carbon nanotube @MnO ₂ dispersion with a concentration of 0.3 mg mL ^-1 with deionized water.

(3) Preparation of porous graphene/carbon nanotube@MnO ₂ composite film material: Measure the dispersion liquid according to the mass ratio of porous graphene and carbon nanotube @MnO ₂ as 1:4, and dilute it to 500mL with deionized water, Ultrasonic treatment was used to disperse it evenly; vacuum filtration was carried out with a mixed cellulose filter membrane (pore size of 0.45 μm); the obtained filter cake was dried naturally in a cool place, and then carefully peeled off to obtain porous graphene/carbon nanotubes@MnO ₂ Composite film material, as shown in Figure 1 and 2, the unit mass of the composite film material is 0.5 mg cm ^-2 .

(4) Preparation of porous graphene/carbon nanotube composite film material: Measure porous graphene dispersion and carbon nanotubes according to the mass ratio of porous graphene and carbon nanotubes to 9:1, and dilute to 500mL with deionized water, Ultrasonic treatment was used to disperse it evenly; vacuum filtration was carried out with a mixed cellulose filter membrane (pore size of 0.45 μm); the obtained filter cake was naturally dried in a cool place, and then carefully peeled off to obtain a porous graphene/carbon nanotube composite film material, the unit mass is 0.5mg cm ^-2 .

Using the obtained porous graphene/carbon nanotube@MnO ₂ composite film material as a supercapacitor electrode material for electrochemical performance testing: the prepared porous graphene/carbon nanotube@MnO ₂ composite film material was cut into 1×1cm ² , Use a hydraulic press to press between two nickel foam current collectors under a pressure of 5 MPa to make an integral electrode without binder and conductive agent. A three-electrode system was used to test the electrochemical performance of the monolithic electrode, in which the porous graphene/carbon nanotube@MnO ₂ composite film monolithic electrode, platinum sheet electrode and saturated calomel electrode were the working electrode, auxiliary electrode and reference electrode, respectively. The liquid is 1mol L ^-1 Na ₂ SO ₄ solution, and the test is carried out in the voltage range of -0.2 ~ 0.8V. All electrochemical tests (cyclic voltammetry, constant current charge and discharge, AC impedance) were performed on Shanghai Chenhua CHI760 E electrochemical workstation.

As shown in Figure 3-5, at a current density of 1Ag ^-1 , its specific capacity can reach 320F g ^-1 , and when the current density increases to 50Ag ^-1 , the specific capacity of the electrode material can still reach 230F g ^-1 . It can maintain 72% of the initial capacity, and at the same time, its capacity retention rate is 110% after 5000 tests by cyclic voltammetry.

The porous graphene/carbon nanotube composite film material is used as the negative electrode, and the porous graphene/carbon nanotube @MnO ₂ composite film material is used as the positive electrode to assemble an asymmetric supercapacitor, which is in a 1mol L ^-1 Na ₂ SO ₄ solution system Next, the test is carried out in the voltage range of 0 ~ 1.8V. All electrochemical tests (cyclic voltammetry, constant current charge and discharge, AC impedance) were performed on Shanghai Chenhua CHI760 E electrochemical workstation.

As shown in Figures 6 and 7, the highest energy density can reach 26.43Wh kg ^-1 .

Example 2

(1) Preparation of porous graphene dispersion: the graphite oxide dispersion was prepared by the Hummers method, the concentration of graphite oxide in the aqueous dispersion was 0.2 mg mL ^-1 , and 100 mL of the graphene oxide suspension was ultrasonically treated for 1 h to make it Disperse evenly; add 0.0545g of KMnO ₄ under continuous stirring, and heat with 800W microwave for 10min; Heated in a water bath for 40min, cooled to room temperature, added 2g of oxalic acid and stirred for at least 12h; suction filtered, the final product was washed with deionized water until neutral, and prepared into a 0.2mg mL ^-1 porous graphene dispersion.

(2) Preparation of carbon nanotube @Fe ₂ O ₃ dispersion: Take 280mg FeCl ₃ 6H ₂ O and add it into 160mL deionized water, stir evenly, add 20mg carbon nanotubes, ultrasonic treatment, so that the carbon nanotubes are uniformly dispersed; then Transfer to an autoclave for 180°C hydrothermal treatment for 12 hours; after cooling to room temperature, filter with suction, wash with deionized water until neutral, and dry in a blast oven at 80°C for 12 hours; prepare 0.5 mg mL ^-1 carbon nanotubes with deionized water @Fe ₂ O ₃ dispersion.

(3) Preparation of porous graphene/carbon nanotube@Fe ₂ O ₃ composite film material: Measure the dispersion liquid according to the mass ratio of porous graphene and carbon nanotube @Fe ₂ O ₃ as 1:1, and deionized water Dilute to 500mL, disperse evenly by ultrasonic treatment; then vacuum filter with mixed cellulose filter membrane (0.45μm pore size); the obtained filter cake is naturally dried in a cool place, and then carefully peeled off to obtain porous graphene/carbon Nanotube@Fe ₂ O ₃ composite thin film material, the unit mass of the composite thin film material is 0.8mg cm ^-2 .

Using the obtained porous graphene/carbon nanotube@Fe ₂ O ₃ composite thin film material as a supercapacitor electrode material for electrochemical performance test: the prepared porous graphene/carbon nanotube@Fe ₂ O ₃ composite thin film material was cut into 1 ×1cm ² , pressed between two pieces of nickel foam current collectors with a hydraulic press under a pressure of 5MPa to make an integral electrode without binder and conductive agent. The porous graphene/carbon nanotube@Fe ₂ O ₃ composite thin film integral electrode, platinum sheet electrode and mercury/mercury oxide electrode are used as the working electrode, auxiliary electrode and reference electrode respectively, and 1mol L ^-1 KOH solution is used as the electrolyte , Electrochemical performance tests were performed in the voltage range of -1.1 to 0V. All electrochemical tests (cyclic voltammetry, constant current charge and discharge, AC impedance) were performed on Shanghai Chenhua CHI760E electrochemical workstation.

When the current density is 1Ag ^-1 , its specific capacity can reach 982F g ^-1 . When the current density increases to 50Ag ^-1 , the specific capacity of the electrode material can still reach 509F g ^-1 , which can maintain 52% of the initial capacity. At the same time, the capacity retention rate was 61% after 2000 tests by cyclic voltammetry.

Example 3

(1) Preparation of porous graphene dispersion: prepare graphite oxide dispersion by Hummers method, the concentration of graphite oxide in the aqueous dispersion is 1mg mL ^-1 , take 100mL of graphene oxide suspension and ultrasonically treat it for 1h to make it uniform Disperse; add 0.7271g of KMnO ₄ under continuous stirring, and heat with 1200W microwave for 8min; when the temperature drops to room temperature, add 50mL of deionized water, 500μL of hydrazine hydrate and 700μL of ammonia; Heated in a water bath for 30 min, cooled to room temperature, added 2 g of oxalic acid and stirred for at least 12 h; suction filtered, and the final product was washed with deionized water until neutral, and prepared into a 0.8 mg mL ^-1 porous graphene dispersion.

(2) Preparation of carbon nanotube @Ni(OH) ₂ dispersion: take 20mg carbon nanotubes and ultrasonically disperse them in 40mL deionized water, add 4mmol NiCl ₂ 6H ₂ O, stir well, add 40mL 0.2M NaOH; then transfer to Heat water at 180°C for 6 hours in an autoclave; cool to room temperature, filter with suction, wash with deionized water until neutral, and dry in a blast oven at 80°C for 12 hours; prepare 0.8 mg mL ^-1 carbon nanotubes@Ni with deionized water (OH) ₂ dispersion.

(3) Preparation of porous graphene/carbon nanotube@Ni(OH) ₂ composite film material: Measure the dispersion liquid according to the mass ratio of porous graphene and carbon nanotube@Ni(OH) ₂ as 1:1, and use Dilute to 500mL with deionized water, disperse evenly by ultrasonic treatment; then carry out vacuum filtration with mixed cellulose filter membrane (0.45μm pore size); the resulting filter cake is naturally dried in a cool place, and then carefully peeled off to obtain porous graphene /carbon nanotube@Ni(OH) ₂ composite thin film material, the unit mass of the composite thin film material is 0.7mg cm ^-2 .

Using the obtained porous graphene/carbon nanotube@Ni(OH) ₂ composite film material as a supercapacitor electrode material for electrochemical performance test: cutting the prepared porous graphene/carbon nanotube@Ni(OH) ₂ composite film material into 1×1cm ² , press it between two pieces of foamed nickel current collectors with a hydraulic press under a pressure of 5 MPa to make an integral electrode without binder and conductive agent. The porous graphene/carbon nanotube@Ni(OH) ₂ composite film monolith electrode, platinum sheet electrode and mercury/mercury oxide electrode were used as the working electrode, auxiliary electrode and reference electrode respectively, and 1mol L ^-1 KOH solution was used as the electrolytic All electrochemical tests (cyclic voltammetry, constant current charge and discharge, AC impedance) were performed on Shanghai Chenhua CHI760 E electrochemical workstation.

When the current density is 1Ag ^-1 , its specific capacity can reach 617F g ^-1 , when the current density increases to 50Ag ^-1 , the specific capacity of the electrode material can still reach 440F g ^-1 , which can maintain 71% of the initial capacity , At the same time, its capacity retention rate is 97% after 5000 cycles of cyclic voltammetry test.

The porous graphene/carbon nanotube @Ni(OH) ₂ composite film material is used as the positive electrode, and the porous graphene/carbon nanotube @Fe ₂ O ₃ composite film material prepared in Example 2 is used as the negative electrode to assemble an asymmetric supercapacitor , and its energy density can reach up to 42Whkg ^-1 under 1mol L ^-1 KOH solution system.

Example 4

(1) Preparation of porous graphene dispersion: Preparation of porous graphene dispersion: adopt Hummers method to prepare graphite oxide dispersion, the concentration of graphite oxide in the aqueous dispersion is 0.8mg mL ^-1 , take 100mL of graphene oxide Ultrasonicate the suspension for 1 hour to make it evenly dispersed; add 0.1454g of KMnO ₄ under constant stirring, and heat with 1100W microwave for 10 minutes; when the temperature drops to room temperature, add 50mL of deionized water, 200μL of hydrazine hydrate and 450μL of ammonia water in sequence ; After mixing evenly, heat in a water bath at 90°C for 60 minutes, add 2 g of oxalic acid and stir for at least 12 hours after cooling to room temperature; filter with suction, wash the final product with deionized water until neutral, and prepare a porous solution with a concentration of 0.5 mg mL ^-1 Graphene dispersion.

(2) Preparation of carbon nanotube @V ₂ O ₅ dispersion: Take 80mL of isopropanol and add 0.2mL of vanadium triisopropoxy (VOT) under stirring. After stirring evenly, add 25mg of carbon nanotubes, ultrasonic treatment, so that The carbon nanotubes were uniformly dispersed; then moved into an autoclave for 10 hours at 200°C; filtered with suction, washed with ethanol, dried in a blast oven at 80°C for 12 hours, and then burned in air at 320°C for 1 hour; prepared with deionized water to make 0.8 mg mL ^-1 carbon nanotube @ V ₂ O ₅ dispersion.

(3) Preparation of porous graphene/carbon nanotube@V ₂ O ₅ composite film material: Measure the dispersion liquid according to the mass ratio of porous graphene and carbon nanotube @V ₂ O ₅ as 1:3, and deionized water Dilute to 500mL, disperse evenly by ultrasonic treatment; then vacuum filter with mixed cellulose filter membrane (0.45μm pore size); the obtained filter cake is naturally dried in a cool place, and then carefully peeled off to obtain porous graphene/carbon Nanotube@V ₂ O ₅ composite thin film material, the unit mass of the composite thin film material is 1.0 mg cm ^-2 .

Using the obtained porous graphene/carbon nanotube@V ₂ O ₅ composite film material as a supercapacitor electrode material for electrochemical performance testing: the prepared porous graphene/carbon nanotube@V ₂ O ₅ composite film material was cut into 1 ×1cm ² , pressed between two pieces of nickel foam current collectors with a hydraulic press under a pressure of 5MPa to make an integral electrode without binder and conductive agent. The porous graphene/carbon nanotube@V ₂ O ₅ composite thin film integral electrode, platinum sheet electrode and saturated calomel electrode were used as the working electrode, auxiliary electrode and reference electrode respectively, and 1mol L ^-1 LiNO ₃ solution was used as the electrolyte , Electrochemical performance tests were performed within the voltage range of -0.8 to 0.2V. All electrochemical tests (cyclic voltammetry, constant current charge and discharge, and AC impedance) were performed on Shanghai Chenhua CHI760E electrochemical workstation.

When the current density is 1Ag ^-1 , its specific capacity can reach 225F g ^-1 , when the current density increases to 50A g ^-1 , the specific capacity of the electrode material can still reach 142F g ^-1 , which can maintain 63% of the initial capacity , At the same time, its capacity retention rate was 62% after 2000 cycles of cyclic voltammetry.

Each embodiment in this specification is described in a progressive manner, each embodiment focuses on the difference from other embodiments, and the same and similar parts of each embodiment can be referred to each other.

The above description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention will not be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (9)

1. A preparation method of a porous graphene-based composite film material is characterized by comprising the following steps:

(1) preparing a porous graphene dispersion liquid: preparing graphite oxide dispersion liquid by a Hummers method, uniformly dispersing by ultrasonic, adding potassium permanganate and carrying out microwave treatment; after cooling, adding hydrazine hydrate and ammonia water in turn under the stirring condition, and heating the obtained mixed system in a water bath; cooling the solution, adding oxalic acid, and stirring; performing suction filtration and washing, and preparing a filter cake into a porous graphene dispersion liquid by using deionized water;

(2) preparing a carbon nano tube @ pseudocapacitance material dispersion liquid: ultrasonically dispersing the carbon nano tube in a solvent, adding metal oxide, metal salt or metal salt plus alkali to obtain a hydrothermal treatment system, and carrying out hydrothermal treatment; after cooling, carrying out suction filtration, washing and drying, and preparing a carbon nanotube @ pseudocapacitance material dispersion liquid by using deionized water;

(3) preparing a composite film material: mixing the porous graphene dispersion liquid and the carbon nanotube @ pseudocapacitance material dispersion liquid, and performing ultrasonic treatment; and (3) carrying out vacuum filtration, naturally drying a filter cake, and stripping to obtain the porous graphene/carbon nanotube @ pseudocapacitor material, namely the composite film material.

2. The method for preparing a porous graphene-based composite thin film material according to claim 1, wherein in the step (1):

the graphite oxide concentration in the graphite oxide dispersion liquid is 0.2-2.0mgmL^-1；

The mass ratio of the potassium permanganate to the graphite oxide is 1:1-8: 1;

the dosage of hydrazine hydrate is 0.05-5mL/150mL mixed system;

the dosage of the ammonia water is 0.3-8mL/150mL mixed system.

3. The method for preparing a porous graphene-based composite thin film material according to claim 1 or 2, wherein in the step (1):

the microwave treatment time is 5-30min, and the power is 800-;

heating in water bath for 10-60min at 90-100 deg.C;

the dosage of the oxalic acid is 2g/150mL of the mixed system, and the mixed system is stirred for at least 12h after the oxalic acid is added.

4. The method for preparing a porous graphene-based composite thin film material according to claim 1, wherein in the step (2):

the pseudocapacitance material comprises a metal oxide or metal hydroxide;

the metal oxide comprises manganese dioxide, ferric oxide, tin dioxide or vanadium pentoxide;

the metal hydroxide includes nickel hydroxide.

5. The method for preparing a porous graphene-based composite thin film material according to claim 1 or 4, wherein in the step (2):

the concentration of the carbon nano tube in the hydrothermal treatment system is 0.1-0.35mgmL^-1；

The concentration of the metal oxide or the metal salt in the hydrothermal treatment system is 5-50 mu molmL^-1；

The hydrothermal treatment temperature is 80-240 ℃ and the time is 1-12 h.

6. The method for preparing a porous graphene-based composite thin film material according to claim 1, wherein in the step (3):

the mass ratio of the porous graphene in the porous graphene dispersion liquid to the carbon nano tube @ pseudocapacitance material in the carbon nano tube @ pseudocapacitance material dispersion liquid is 1:4-3: 1.

7. A porous graphene-based composite thin film material prepared by the preparation method of any one of claims 1-6.

8. The porous graphene-based composite film material according to claim 7, wherein the unit mass of the composite film material is 0.5-2mgcm^-2。

9. Use of the porous graphene-based composite thin film material of claim 7 or 8 as an electrode material in a flexible supercapacitor.