CN1995132A - Preparation method of conductive high polymer and carbon nanotube composite electrode material - Google Patents

Abstract

The invention discloses a method for preparing a composite electrode material of a conductive polymer and a carbon nanotube, that is, a conductive polymer (polypyrrole, polyaniline or polythiophene and their derivatives) and a carbon nanotube (single-walled or multi-walled) for a supercapacitor. wall) composite electrode preparation method, the carbon nanotubes are dispersed in the polymerization solution with a conventional surfactant. Not only the synergistic effect of carbon nanotubes and polymers can increase the specific capacity of the composite, but also the hollow structure of carbon nanotubes can absorb the volume shrinkage and expansion caused by the charge and discharge of polymer materials, and the high conductivity of carbon nanotubes can reduce the composite capacity. resistance of the object. Therefore, the prepared conductive polymer/carbon nanotube electrode material has high specific capacity (over 200 F/g), low internal resistance and fast charge and discharge capability. Supercapacitors prepared with this type of electrode material have the advantages of high specific power (Specific Power), high specific energy (Specific Energy) and long life.

Description

Preparation method of conductive polymer and carbon nanotube composite electrode material

technical field

The invention relates to a preparation method of a novel electronic material, in particular to a preparation method of a conductive polymer and carbon nanotube composite electrode material.

Background technique

With the gradual depletion of petrochemical resources and its increasingly serious impact on the environment and ecology, more and more attention has been paid to saving and using energy efficiently and cleanly. As one of the high-efficiency energy storage and energy conversion devices, supercapacitors (electrochemical capacitors) have received extensive attention. The electrode material is the decisive factor for the performance of supercapacitors. Due to the existence of different oxidation states, conductive polymers (polypyrrole, polyaniline, polythiophene, polyphenylene, and their derivatives and other conjugated polymers) can be used as electrode materials for redox supercapacitors. Compared with other two common types of supercapacitor electrode materials (carbon materials and metal oxides), conductive polymer materials (also known as conductive polymers) have higher Specific capacity and specific energy (Specific Energy), lower cost than metal oxides (such as ruthenium oxide). The preparation of conductive polymer capacitor electrodes by electrochemical methods can be simpler than carbon materials and metal oxide materials. Therefore, conductive polymer materials are a class of very practical supercapacitor electrode materials.

However, when the conductive polymer electrode material is discharged, the doped counter-ions are released from the polymer grid and enter the electrolyte (counter-ion dedoping), which will cause the volume shrinkage of the polymer and affect the intercalation and polymerization of counter-ions during charging. The capacity of the polymer is reduced due to the mesh network, and multiple shrinkage and expansion will lead to increased defects in the polymer film and affect the cycle stability of the electrode. The conductivity of the polymer will drop sharply when it is in the discharged state (dedoped state), which will greatly increase the internal resistance of the capacitor.

Contents of the invention

The purpose of the present invention is to provide a preparation method of a conductive polymer and carbon nanotube composite electrode material capable of enhancing the capacity performance and cycle stability of the conductive polymer.

In order to achieve the above-mentioned purpose, the technical scheme adopted in the present invention is: firstly, ultrasonically vibrate the carbon nanotubes in a 0.01-0.6mol/L surfactant solution for 5min-2h to obtain a 0.01-0.1wt% carbon nanotube-containing dispersion Solution A; secondly, add conductive polymer monomer to solution A or diluted solution of A to make the concentration of conductive polymer monomer 0.01mol/L～0.6mol/L; then add supporting electrolyte to make the concentration of supporting electrolyte 0mol/L L～0.3mol/L to prepare solution B; finally put the working electrode and counter electrode in solution B, apply 0.1～10mA/cm ² current density to the working electrode for electrochemical polymerization, after the polymerization is completed, the working electrode can be A layer of uniform conductive polymer/carbon nanotube composite film can be obtained on the surface, and the thickness of the composite film can be controlled by multiplying the polymerization electricity, that is, the polymerization current by the polymerization time.

The carbon nanotubes of the present invention are single-wall carbon nanotubes or multi-wall carbon nanotubes; the surfactant is an anionic surfactant: dodecylbenzenesulfonate solution or p-toluenesulfonate solution, and its cation is a hydrogen ion , sodium ion or potassium ion; or cationic surfactant: tetraalkylammonium solution, the alkyl group is ethyl or butyl, the anion is perchlorate, chloride ion or bromide ion; the conductive polymer monomer is pyrrole, aniline, Thiophene or their derivatives methylpyrrole or ethylenedioxythiophene; the supporting electrolyte is chloride, perchlorate or nitrate.

The invention utilizes the high conductivity and hollow structure of carbon nanotubes to enhance the capacity performance and cycle stability of conductive polymers by preparing conductive polymers and carbon nanotube composites. Since carbon nanotubes are easy to agglomerate, it is difficult to disperse in the solution , the present invention first disperses the carbon nanotubes with a surfactant, and then adds monomers for chemical or electrochemical polymerization to prepare a polymer/carbon nanotube composite material as a supercapacitor electrode material.

Description of drawings

Fig. 1 is the electron micrograph of polypyrrole/carbon nanotube composite material;

Figure 2(a) and (b) respectively show the cyclic voltammetry curves of pure polypyrrole film and polypyrrole/carbon nanotube composite, where the abscissa is the potential and the ordinate is the current;

Fig. 3 is the specific capacity of simple polypyrrole film (1) and polypyrrole/carbon nanotube composite material (2) at different scan rates, where the abscissa is the scan rate, and the ordinate is the specific capacity.

Detailed ways

The present invention will be described in further detail below in conjunction with the accompanying drawings.

Embodiment 1: first single-walled carbon nanotubes were ultrasonically oscillated in 0.6mol/L dodecylbenzenesulfonic acid solution for 5 minutes to obtain a dispersion A containing 0.01wt% of carbon nanotubes; Add conductive polymer monomer pyrrole to the diluted solution of A so that the concentration of conductive polymer monomer pyrrole is 0.6mol/L to prepare solution B; finally place the working electrode and counter electrode in solution B, and apply 10mA to the working electrode /cm ² current density for electrochemical polymerization. After the polymerization is completed, a uniform conductive polymer/carbon nanotube composite film can be obtained on the working electrode. The thickness of the composite film can be multiplied by the polymerization electricity, that is, the polymerization current time to control.

Embodiment 2: first multi-walled carbon nanotubes were ultrasonically oscillated in 0.2mol/L sodium dodecylbenzenesulfonate solution for 20 minutes to obtain a dispersion A containing 0.05wt% of carbon nanotubes; Or in the dilute solution of A, add conductive macromolecular monomer aniline to make the concentration of conductive macromolecular monomer aniline be 0.05mol/L; Then add chloride so that the concentration of chloride is 0.1mol/L to make solution B; The working electrode and the counter electrode are placed in solution B, and a current density of 8mA/ ^cm2 is applied to the working electrode for electrochemical polymerization. After the polymerization is completed, a uniform layer of conductive polymer/carbon nanotube composite can be obtained on the working electrode. Membrane, the thickness of the composite membrane can be controlled by the polymerization charge, that is, the polymerization current multiplied by the polymerization time.

Embodiment 3: first the single-walled carbon nanotubes were ultrasonically oscillated in 0.4mol/L potassium toluenesulfonate solution for 50 minutes to obtain a dispersion A containing 0.08wt% of carbon nanotubes; Add conductive polymer monomer thiophene to make the concentration of conductive polymer monomer thiophene 0.2mol/L in the diluted solution; then add perchlorate so that the concentration of perchlorate is 0.05mol/L to make solution B; Finally, place the working electrode and the counter electrode in solution B, and apply a current density of 5mA/cm ² to the working electrode for electrochemical polymerization. After the polymerization is completed, a uniform layer of conductive polymer/carbon nanotubes can be obtained on the working electrode The composite film, the thickness of the composite film can be controlled by the polymerization electricity, that is, the polymerization current multiplied by the polymerization time.

Embodiment 4: first multi-walled carbon nanotubes were ultrasonically oscillated in 0.01mol/L toluenesulfonic acid solution for 45 minutes to obtain a dispersion A containing 0.04wt% of carbon nanotubes; Add conductive polymer monomer methylpyrrole to make the concentration of conductive polymer monomer methylpyrrole in the diluted solution be 0.4mol/L; then add nitrate so that the concentration of nitrate is 0.2mol/L to make solution B; finally Place the working electrode and the counter electrode in solution B, and apply a current density of 3mA/cm ² to the working electrode for electrochemical polymerization. After the polymerization is completed, a uniform layer of conductive polymer/carbon nanotube can be obtained on the working electrode. Composite membrane, the thickness of the composite membrane can be controlled by the polymerization electricity, that is, the polymerization current multiplied by the polymerization time.

Embodiment 5: First, single-walled carbon nanotubes are ultrasonically oscillated in 0.05mol/L tetraethylammonium perchlorate solution for 1h to obtain a dispersion A containing 0.09wt% of carbon nanotubes; Add conductive polymer monomer ethylenedioxythiophene to make the concentration of conductive polymer monomer ethylenedioxythiophene 0.01mol/L in the diluted solution; then add chloride so that the concentration of chloride is 0.3mol/L to prepare a solution B; Finally, place the working electrode and the counter electrode in solution B, and apply a current density of 1mA/cm ² to the working electrode for electrochemical polymerization. After the polymerization is completed, a uniform layer of conductive polymer/carbon can be obtained on the working electrode A composite film of nanotubes, the thickness of which can be controlled by multiplying the polymerization electricity, that is, the polymerization current multiplied by the polymerization time.

Embodiment 6: First multi-walled carbon nanotubes are ultrasonically oscillated in 0.08mol/L tetrabutylammonium perchlorate solution for 1.5h to obtain a dispersion A containing 0.06wt% of carbon nanotubes; Add conductive polymer monomer pyrrole to the diluted solution of A to make the concentration of conductive polymer monomer pyrrole be 0.05mol/L; then add chloride so that the concentration of chloride is 0.3mol/L to make solution B; The electrode and the counter electrode are placed in solution B, and a current density of 0.5 mA/ ^cm2 is applied to the working electrode for electrochemical polymerization. After the polymerization is completed, a uniform layer of conductive polymer/carbon nanotube composite can be obtained on the working electrode. Membrane, the thickness of the composite membrane can be controlled by the polymerization charge, that is, the polymerization current multiplied by the polymerization time.

Embodiment 7: First, single-walled carbon nanotubes are ultrasonically oscillated in 0.3mol/L tetraethylammonium chloride solution for 1.2h to obtain a dispersion A containing 0.02wt% of carbon nanotubes; Add conductive polymer monomer aniline to make the concentration of conductive polymer monomer pyrrole be 0.3mol/L in the diluted solution of conductive polymer; Then add perchlorate to make the concentration of perchlorate be 0.15mol/L to make solution B; Finally, place the working electrode and the counter electrode in solution B, and apply a current density of 0.1mA/cm ² to the working electrode for electrochemical polymerization. After the polymerization is completed, a uniform layer of conductive polymer/carbon nanometer can be obtained on the working electrode. The composite film of the tube, the thickness of the composite film can be controlled by the polymerization electricity, that is, the polymerization current multiplied by the polymerization time.

Embodiment 8: First, multi-walled carbon nanotubes are ultrasonically oscillated in 0.05mol/L tetrabutylammonium bromide solution for 2h to obtain a dispersion A containing 0.1wt% of carbon nanotubes; Add conductive polymer monomer ethylenedioxythiophene to the diluted solution so that the concentration of conductive polymer monomer ethylenedioxythiophene is 0.08mol/L; then add nitrate so that the concentration of nitrate is 0.25mol/L to prepare solution B ; Finally, the working electrode and the counter electrode are placed in solution B, and a current density of 0.8mA/ ^cm2 is applied to the working electrode for electrochemical polymerization. After the polymerization is completed, a uniform layer of conductive polymer/carbon can be obtained on the working electrode. A composite film of nanotubes, the thickness of which can be controlled by multiplying the polymerization electricity, that is, the polymerization current multiplied by the polymerization time.

Referring to Figure 1, it can be seen from the figure that the carbon nanotubes are coated with polypyrrole, and large-area polypyrrole can be connected together, which can effectively increase the electronic conductivity of the composite. In this composite material, carbon nanotubes can not only contribute to the capacitance of the electric double layer and improve the conductivity of the composite, but also its hollow structure can absorb the volume shrinkage and expansion caused by the charge and discharge of the polymer, so the composite has a faster Charge and discharge characteristics.

Referring to Fig. 2, it can be seen from Fig. 2(a) that when the scan rate is 10mV/s, the polypyrrole film electrode shows a relatively ideal supercapacitor cyclic voltammetry curve (close to a rectangle), but as the scan rate increases , the polypyrrole film gradually exhibits a cyclic voltammetry curve similar to resistance. However, the composite of polypyrrole/carbon nanotubes still exhibits a relatively ideal cyclic voltammetry curve of supercapacitors at a scan rate of 200mV/s, as shown in Figure 2(b). When the scan rate is 10mV/s, the specific capacity of the polypyrrole/carbon nanotube composite exceeds 200F/g, and when the scan rate is 200mV/s, the specific capacity is still 71.1% of the scan rate of 10mV/s, while When the scan rate of pure polypyrrole film is 200mV/s, the specific capacity is only 13.6% of the scan rate of 10mV/s. As shown in Figure 3. Therefore, the prepared conductive polymer/carbon nanotube electrode material has high conductivity, high specific capacity, ultra-fast charge and discharge capability, and good stability. Therefore, the composite material can be made into a supercapacitor with high specific energy, high specific power and long life.

Claims (5)

1, the preparation method of conducting polymer and carbon nano-tube combination electrode material is characterized in that:

1) at first with carbon nanotube sonic oscillation 5min～2h in the surfactant soln of 0.01～0.6mol/L, makes the dispersion liquid A of carbon nanotubes 0.01～0.1wt%;

Secondly 2) adding conductive high polymer monomer in the diluting soln of A solution or A, to make conductive high polymer monomer concentration be 0.01mol/L～0.6mol/L; And then add to support ionogen and make that to support electrolytical concentration be that 0mol/L～0.3mol/L makes solution B;

3) at last working electrode and counter electrode are placed solution B, on working electrode, apply 0.1～10mA/cm ²Current density is carried out electrochemical polymerization, can obtain the composite membrane of layer of even conducting polymer/carbon nanotube after polymerization is finished on working electrode, and the thickness of this composite membrane can be that the polymerization electric current multiply by polymerization time and controls by the polymerization electric weight.

2, the preparation method of conducting polymer according to claim 1 and carbon nano-tube combination electrode material is characterized in that: said carbon nanotube is Single Walled Carbon Nanotube or multi-walled carbon nano-tubes.

3, the preparation method of conducting polymer according to claim 1 and carbon nano-tube combination electrode material, it is characterized in that: said tensio-active agent is an anion surfactant: Witco 1298 Soft Acid root solution or p-methyl benzenesulfonic acid root solution, and its positively charged ion is hydrogen ion, sodium ion or potassium ion; Or cats product: tetra-allkylammonium solution, alkyl are ethyl or butyl, and negatively charged ion is perchlorate, chlorion or bromide anion.

4, the preparation method of conducting polymer according to claim 1 and carbon nano-tube combination electrode material is characterized in that: said conductive high polymer monomer is pyrroles, aniline, thiophene or their derivative methylpyrrole or ethene dioxythiophene.

5, the preparation method of conducting polymer according to claim 1 and carbon nano-tube combination electrode material is characterized in that: said support ionogen is muriate, perchlorate or nitrate.

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