KR20200126287A - Carbon nanotube oxide composites for stretchable energy storage element, and method for producing carbon nanotube oxide composites, and stretchable energy storage element including the same - Google Patents

Abstract

The present invention relates to a method for manufacturing a carbon nanotube oxide composite for a stretchable energy storage element, a carbon nanotube oxide composite manufactured thereby, and a stretchable energy storage element including the same and, more specifically, to a method for manufacturing a carbon nanotube oxide composite for a stretchable energy storage element, which provides excellent energy storage properties and electric conductivity while having a unique stretchability to be used for an electrode, a carbon nanotube oxide composite manufactured thereby, and a stretchable energy storage element including the same. According to the present invention, the method comprises an oxidation step of oxidizing a carbon nanotube to form an oxidized carbon nanotube and a complex forming step of mixing the oxidized carbon nanotube with a polymer and an electrolyte to form a paste-shaped oxidized carbon nanotube complex.

Description

Carbon nanotube oxide composites for stretchable energy storage element, and method for producing carbon nanotube oxide composites, including a method of manufacturing a carbon oxide nanotube composite for a stretchable energy storage device and a carbon oxide nanotube composite prepared therefrom, and stretchable energy storage element including the same}

The present invention relates to a method of manufacturing a carbon oxide nanotube composite for a stretchable energy storage device, a carbon oxide nanotube composite prepared therefrom, and a stretchable energy storage device including the same, and more specifically, to a stretchable energy storage device having inherent stretchability and The present invention relates to a method of manufacturing a carbon oxide nanotube composite for a flexible energy storage device that has excellent electrical conductivity and can be used as an electrode, a carbon oxide nanotube composite manufactured therefrom, and a new energy storage device including the same.

Due to the development of various electronic devices such as computers, notebook computers, and electric vehicles, interest in energy storage devices with higher performance is rising, which is showing rapid growth. Representative examples of current energy storage devices include secondary batteries, super capacitors and micro super capacitors. .

For example, a supercapacitor has a high power density because it instantly releases a high current quickly after storing energy, and charging and discharging occurs while the ions of the electrolyte are adsorbed and desorbed on the electrode surface. This is possible, and because the performance is maintained even when rapid charging/discharging is repeated many times, it can be used semi-permanently.

In addition, micro super capacitors were developed to provide a power density that is several times higher than that of super capacitors. Due to the short ion diffusion distance, the power density is high. More importantly, it is used with other devices such as micro batteries and micro energy harvesting systems. There is an advantage of being able to directly integrate the device, an advantage of being able to be manufactured in a form that can be deformed, and an advantage of being applicable to micro robots or wearable electronic fabrics due to their small size and volume.

Electrodes used in these energy storage devices include activated carbon powder, activated carbon fiber, carbon aerogel, carbon nanotube (CNT), and graphene. Carbon materials such as can be applied. Among them, carbon nanotubes are microscopic molecules with a diameter of less than tens of nm in which carbons connected by hexagonal rings form a tube shape.Thus, three carbon atoms are bonded to have a honeycomb structure. It is formed by rolling a carbon plane into a tube shape, and is based on excellent properties such as mechanical strength, chemical stability, thermal conductivity, and electrical conductivity.

In particular, in recent years, with the rapid rise of various flexible flexible devices or wearable devices, attention has been focused on energy storage devices having elasticity to be applicable thereto.

As such, an energy storage device having elasticity has been manufactured by grafting a buckled structure to the electrode through a series of processes of lamination of a film-type electrode made of carbon nanotubes to a corrugated and stretchable substrate.

1 is a problem of a conventional corrugated electrode, which shows a problem that occurs when a film-type electrode made of carbon nanotubes is bonded to a corrugated and stretchable substrate. Referring to FIG. 1, a phenomenon in which defects occur during the buckling process is shown, and the film-shaped electrode itself does not have elasticity, but FIGS. 1-(a), 1-(b), and FIG. As shown in (c), since the buckling process is performed to form a corrugated structure on the electrode, it can be seen that there is a problem of causing a decrease in elasticity due to poor bonding between the substrate and the electrode interface.

That is, the exposure or solvent impregnation process required for the formation of the electrode structure is required, so that the use of a photosensitive material is impossible, and because the substrate and carbon nanotubes are bonded, the performance is limited according to the stretching direction, Since there is a cumbersome problem due to the need for an additional lamination process, it is the time when a research on technology development to be used as an electrode with excellent energy storage and electrical conductivity while having inherent elasticity is urgently required.

Registered Korean Patent Publication No. 10-1742593, as of May 26, 2017.

The present invention has been invented to solve the above problems, and has inherent elasticity and excellent energy storage and electrical conductivity, so that it can be used as an electrode, a method of manufacturing a carbon oxide nanotube composite for a new energy storage device, and manufacturing therefrom. The purpose of this is to provide a carbon oxide nanotube composite, a flexible energy storage device including the same.

The present invention for achieving the above object, the oxidation treatment step of forming carbon oxide nanotubes by oxidation treatment of carbon nanotubes; And a complexing step of forming a paste-type carbon oxide nanotube composite by mixing a polymer and an electrolyte with the carbon oxide nanotubes; the technical summary of a method of manufacturing a carbon oxide nanotube composite for a flexible energy storage device comprising: To

Preferably, in the oxidation treatment step, at least one of sodium chlorate (NaClO ₃ ), sodium perchlorate (NaClO ₄ ), potassium chlorate (KClO ₃ ) and potassium perchlorate (KClO ₄ ) in the carbon nanotubes, and It is characterized in that it is oxidized by reacting one or more strong acids among fuming nitric acid, sulfuric acid, nitric acid, hydrochloric acid, phosphoric acid and hydrogen peroxide. To do.

Preferably, between the oxidation treatment step and the complexing step, the carbon oxide nanotubes are centrifuged to neutralize the pH to 7 to separate the supernatant and the precipitate, and then the carbon oxide nanotubes in the form of a paste are separated from the precipitate. It characterized in that it further comprises a; centrifugation step to obtain.

Preferably, after the complexing step, a film forming step of forming the carbon oxide nanotube composite in the form of a paste into a carbon oxide nanotube composite in the form of a film having elasticity by a solvent casting method; characterized in that it further comprises do.

The present invention for achieving the above object is a carbon oxide nanotube composite for a flexible energy storage device, characterized in that it is formed by mixing carbon oxide nanotubes formed by oxidation treatment of carbon nanotubes, a polymer and an electrolyte, and thus has elasticity. Make it a technical point.

The present invention for achieving the above object, the separation membrane; And a positive electrode and a negative electrode disposed on both sides of the separator, wherein the positive electrode and the negative electrode are formed by mixing carbon oxide nanotubes, a polymer, and an electrolyte formed by oxidation treatment of carbon nanotubes, thereby having elasticity. A new energy storage device including the characteristic carbon oxide nanotube composite is also a technical point.

The method of manufacturing a carbon oxide nanotube composite for a flexible energy storage device according to the present invention by means of solving the above problems, and a carbon oxide nanotube composite manufactured therefrom, and a flexible energy storage device including the same, are oxidized carbon oxide nanotubes, Since the carbon oxide nanotube composite itself composed of a polymer and an electrolyte has inherent elasticity and excellent energy storage and electrical conductivity, there is an effect that can be directly applied as an electrode of a flexible energy storage device.

1 is a problem of a conventional corrugated electrode.
2 is a carbon oxide nanotube composite according to a preferred embodiment of the present invention.
Figure 3 is a schematic diagram of the expansion and charging / discharging of the carbon oxide nanotube composite according to a preferred embodiment of the present invention.
4 is a carbon nanotube and a carbon oxide nanotube according to a preferred embodiment of the present invention.
5 is a photograph of film formation through carbon oxide nanotubes according to a preferred embodiment of the present invention.
6 is a photograph of film formation through carbon nanotubes.
7 is a structural diagram of a new supercapacitor according to a preferred embodiment of the present invention.
8 is a structural diagram of a stretchable micro super capacitor according to a preferred embodiment of the present invention.
9 is a photograph of a stretch micro super capacitor according to a preferred embodiment of the present invention.
10 is a strain experiment of FIG. 9.
11 is an XPS analysis result according to a preferred embodiment of the present invention.
12 is a Stress-Strain characteristic according to a preferred embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

2 is a carbon oxide nanotube composite according to a preferred embodiment of the present invention. Referring to FIG. 2, it can be seen that a carbon oxide nanotube composite formed of a mixture of carbon oxide nanotubes, a polymer, and an electrolyte formed by oxidation treatment of carbon nanotubes is applied as an electrode having inherent elasticity.

FIG. 2-(a) is a photograph showing a state before the electrode based on a carbon oxide nanotube composite consisting of a carbon oxide nanotube, a polymer and an electrolyte is stretched, and FIG. 2-(b) is shown in FIG. 2-(a). It can be seen that this is a picture showing the shape of the electrode after being stretched without breaking when pulled by hand.

Figure 3 is a schematic diagram of the expansion and charging / discharging of the carbon oxide nanotube composite according to a preferred embodiment of the present invention. Referring to FIG. 3, it can be seen that the carbon oxide nanotube composite forms an electrode to expand and contract or charge/discharge.

Figure 3- (a) schematically shows the electrode of Figure 2- (a), single-walled carbon nanotubes (single-walled carbon nanotubes, SWCNT) oxidation-treated carbon oxide nanotubes, polymer and It can be seen that the electrolyte (PO ₄ ^3- , H ⁺ ) is an electrode formed in a coexisting state. Fig. 3-(b) schematically shows the electrode of Fig. 2-(b), and it can be seen that it is possible to expand and contract without breaking when the electrode of Fig. 3-(a) is pulled. Figure 3- (c) is intended only to show the subject to charging / discharging, the electron (e ^-) it can be seen that shows the charging or discharging are possible while the absorption or talchal the electrode surface.

The carbon oxide nanotube composite that can be applied as an electrode in this way can be prepared through an oxidation treatment step (S10), a centrifugation step (S20), a complexing step (S30), and a film forming step (S40). It can be described as follows.

First, the oxidation treatment step is a step of oxidizing carbon nanotubes to form carbon oxide nanotubes. (S10)

That is, the oxidation treatment step is any one of sodium chlorate (NaClO ₃ ), sodium perchlorate (NaClO ₄ ), potassium chlorate (KClO ₃ ) and potassium perchlorate (KClO ₄ ) in a single-walled or double-walled or multi-walled carbon nanotube. Oxidation by reacting the above oxidizing agent with any one or more of fuming nitric acid, sulfuric acid, nitric acid, hydrochloric acid, phosphoric acid, and hydrogen peroxide. By treatment, it refers to a step of pretreatment so that the polymer and electrolyte are well dispersed in the carbon oxide nanotubes.

At this time, it is preferable to mix the carbon nanotubes and the oxidizing agent in a weight ratio of 1:5 to 10.If the oxidizing agent is less than 5 weight ratio, the carbon nanotubes are not sufficiently oxidized, and if the oxidizing agent exceeds 10 weight ratio, the degree of oxidation of the carbon nanotubes is excessive. This is because the electrical conductivity of carbon oxide nanotubes can be reduced.

And it is preferable to mix the carbon nanotubes and the strong acid in a weight ratio of 1:15 to 20. If the strong acid is added in a weight ratio of less than 15 weight ratio, it may be insufficient to induce the reaction, and if it is added in excess of 20 weight ratio, damage to the carbon nanotubes is caused. This is because it can not be completed with carbon oxide nanotubes.

4 is a carbon nanotube and a carbon oxide nanotube according to a preferred embodiment of the present invention. Fig. 4-(a) shows the carbon nanotubes before oxidation treatment, and it can be seen that the photos of the carbon nanotubes are entangled with each other. Fig. 4-(b) is a photograph showing carbon oxide nanotubes formed by oxidation treatment of carbon nanotubes before oxidation treatment shown in Fig. 4-(a), and ions of an electrolyte may be adsorbed or desorbed to carbon oxide nanotubes. It is confirmed that pores are created.

As shown in Fig. 4-(b), the completed carbon oxide nanotubes collect ions in the electrolyte to the surface of the carbon oxide nanotubes to store energy. When the stored energy is to be used, it is adsorbed on the surface of the carbon oxide nanotubes. By acting as a pore to allow the ions of the existing electrolyte to be desorbed, it serves to improve energy storage.

In addition, since carbon oxide nanotubes have electrical conductivity, they play a role of allowing electrons to move freely back and forth to the carbon oxide nanotubes.

If it is made into a paste by mixing carbon nanotubes, polymers and electrolytes instead of carbon oxide nanotubes, it cannot be used as an electrode because there is no elasticity, no electrical conductivity, or even if there is elasticity and electrical conductivity, the electrolyte cannot enter. , Carbon oxide nanotubes can be said to play an important role.

Next, the centrifugation step is a step of centrifuging the carbon oxide nanotubes to neutralize the pH to 7 to separate the supernatant and the precipitate, and then obtaining the carbon oxide nanotubes in the form of a paste from the precipitate. (S20)

Following the oxidation treatment step, the centrifugation step is an additional step.When the supernatant becomes transparent by neutralizing the carbon oxide nanotubes that have been subjected to oxidation treatment, acid is added and centrifuged again, and then additional acid is added until the pH reaches 7. By neutralizing by centrifugation, a paste-type carbon oxide nanotube is finally obtained from the sediment separated from the supernatant.

At this time, the solid content of the carbon oxide nanotubes present in the carbon oxide nanotubes in the form of a paste is preferably 0.1 to 5 wt%. If it is less than 0.1 wt%, not only is the electrical conductivity of the carbon oxide nanotube composite unsatisfactory, but also results in unsatisfactory results in the carbon oxide nanotubes performing the pore role, whereas if it exceeds 5 wt%, it is rather carbon oxide. This is because it can cause side effects in playing the natural role of the nanotube.

Next, the complexing step is a step of forming a carbon oxide nanotube composite in the form of a paste by mixing a polymer and an electrolyte with the carbon oxide nanotubes. (S30)

In other words, the complexing step is to make the carbon nanotubes into a form that can be used as an electrode by mixing a polymer and an electrolyte with oxidized carbon oxide nanotubes, which have inherent elasticity and excellent energy storage and electrical conductivity. Step.

In the case of a polymer, it serves as a support, and for example, any one or more of polyvinyl alcohol, polyvinyl pyrrolidone, and polyethylene glycol may be selectively used. However, in the present invention, polyvinyl alcohol is applied, but any polymer that can serve as a support may be applied.

For reference, carbon oxide nanotubes and polymers can be mixed in a weight ratio of 1 to 10:90 to 99, that is, oxidation only when carbon oxide nanotubes and polymers are properly mixed within the range of 1 to 10:90 to 99 weight ratio. It was confirmed that the electrical conductivity of the carbon nanotube composite, the provision of pores for ion storage, and the role of the support were optimally achieved.

In the case of an electrolyte, it provides ions, which is the original role of the electrolyte, to the carbon oxide nanotube composite and provides elasticity. That is, in the field requiring only electrical conductivity, carbon nanotubes and polymers may be mixed and used, but in the present invention, energy storage is required, so an electrolyte is required.

If it contains a large amount of electrolyte to improve the elasticity, less carbon oxide nanotubes enter, resulting in poor electrical conductivity, whereas if a large amount of carbon oxide nanotubes are included to improve electrical conductivity, ions of the electrolyte cannot enter. , It is preferable that the carbon oxide nanotubes and the electrolyte are made in a weight ratio of 1:90 to 95.

Finally, in the film forming step, the carbon oxide nanotube composite in the form of a paste is formed into a carbon oxide nanotube composite in the form of a film having elasticity by a solvent casting method. (S40)

That is, in the film forming step, a paste-type carbon oxide nanotube composite consisting of carbon oxide nanotubes, a polymer, and an electrolyte is manufactured into a film-type carbon oxide nanotube composite through a solvent casting method so that it can be used as an electrode. Step.

5 is a photograph of film formation through carbon oxide nanotubes according to a preferred embodiment of the present invention. FIG. 5-(a) is a photograph showing a carbon oxide nanotube composite in the form of a paste made of carbon oxide nanotubes, a polymer, and an electrolyte, and FIG. 5-(b) is an oxidation in the paste form shown in FIG. 5-(a). This is a photograph showing a carbon oxide nanotube composite in the form of a film prepared by a solvent casting method of a carbon nanotube composite.

6 is a photograph of film formation through carbon nanotubes. In other words, FIG. 6 shows that unlike FIG. 5 in which carbon oxide nanotubes are used, carbon nanotubes that are not oxidized, polymers, and electrolytes are mixed, and the resulting film is formed.

In other words, FIG. 6-(a) is a photograph showing a paste made of carbon nanotubes, polymers, and electrolytes. Unlike the paste-type carbon oxide nanotube composites shown in FIG. 5-(a), carbon nanotubes without oxidation treatment It can be seen that the tube is applied and is not formed in a stable paste form. In addition, although FIG. 6-(b) is made of the unstable paste of FIG. 6-(a) in the form of a film, it can be seen that a great force is required to pull, so that the elasticity is not good, and a tendency to break appears. .

7 is a structural diagram of a new supercapacitor 100 according to a preferred embodiment of the present invention. Referring to FIG. 7, it can be seen that the structure of a stretchable supercapacitor 100 provided with an anode 120 and a cathode 140 on both sides of the stretchable electrolyte 160 as an example is shown. That is, by applying the carbon oxide nanotube composite of the present invention to the anode 120 and cathode 140 of FIG. 7, it can be used as a new energy storage device.

8 is a structural diagram of a stretch micro super capacitor 200 according to a preferred embodiment of the present invention. Referring to FIG. 8, an anode 240 and a cathode 260 are disposed on a substrate 220, and an electrolyte 280 is in contact with the anode 240 and the cathode 260. It can be seen that the structure is shown as an example. Like FIG. 7, the carbon oxide nanotube composite of the present invention is applied to the anode 240 and the cathode 260 of FIG. 8, so that it can be used as a new energy storage device.

9 is a photograph of a telescopic micro super capacitor 200 according to a preferred embodiment of the present invention. Referring to FIG. 9, it can be seen that the stretch micro super capacitor 200 of FIG. 8 is actually made of a printed stretch micro super capacitor 200.

That is, on the current collector made of silver (Ag) / carbon oxide nanotubes (CNT) / polydimethyl sulfoxide (PDMS), as carbon oxide nanotubes (CNT) / polyvinyl alcohol (PVA) / phosphoric acid (H ₃ PO ₄ ). It can be seen that the positive electrode 240 and the negative electrode 260 are disposed, and the electrolyte 280 made of polyvinyl alcohol (PVA)/polydimethyl sulfoxide (PDMS) is disposed on the positive electrode 240 and the negative electrode 260. .

10 is a strain experiment of FIG. 9. Fig. 10-(a) is a picture showing a state of 0% not pulled by hand, and Fig. 10-(b) is a picture showing a state of being pulled by 20% by hand, and the force on the elastic micro super capacitor 200 It is confirmed that the elasticity is good even if it is pulled by applying.

Hereinafter, examples and comparative examples of the present invention will be described in detail.

<Example 1>

Finely grind 15 g of sodium chlorate (NaClO ₃ ) using a mortar and a mortar and mix with 2 g of carbon nanotubes. After that, it is mixed with 40 mL of fuming nitric acid, kneaded using a Teflon spatula, and reacted for 1 hour. After completion of the reaction, neutralization is performed using deioniaed water and a centrifuge. When the supernatant becomes transparent, 200 mL of hydrochloric acid (HCl) is added. After adding hydrochloric acid, centrifugation, 100 mL of hydrogen peroxide (H ₂ O ₂ ) is added again, and then centrifuged until the pH reaches 7 to neutralize. After that, the purification process is repeated 3 to 5 times, and the paste from which the supernatant is finally removed is collected. At this time, the solid content of carbon oxide nanotubes present in the paste is 0.1-5 wt%, and the paste equivalent to 40 mg of carbon oxide nanotubes is taken out into the paste mixer container. In addition, 5 g of polyvinyl alcohol (PVA, Mw=80,000~120,000) is dissolved in 45 g of deionized water, and then 36.9 g of the solvent is mixed using a paste-type carbon oxide nanotube and a paste mixer. At this time, the weight ratio of carbon oxide nanotubes and PVA is 1:99. 3.69 g of phosphoric acid (H ₃ PO ₄ ) is added to the mixed paste and mixed again using a paste mixer. A film is prepared from the prepared paste by a solvent casting method.

<Example 2>

A film-type carbon oxide nanotube composite was prepared in the same manner as in Example 1, except that the weight ratio of carbon oxide nanotubes and PVA was 5:95.

<Example 3>

A film-type carbon oxide nanotube composite was prepared in the same manner as in Example 1, except that the weight ratio of carbon oxide nanotubes and PVA was 10:90.

<Example 4>

Finally, to the paste from which the supernatant was removed, dimethylsulfoxide (DMSO), which is 100 times the weight of the carbon oxide nanotubes, was added and deionized water was removed using a solvent evaporator, and PVA was dissolved in the DMSO solvent. Except for manufacturing, in the same manner as in Example 1, a film-type carbon oxide nanotube composite was prepared.

11 is an XPS analysis result according to a preferred embodiment of the present invention. Referring to FIG. 11, according to the binding energy of Example 1 corresponding to the case of carbon oxide nanotubes in which carbon nanotubes are oxidized and Comparative Example 1 corresponding to the case of carbon nanotubes not subjected to oxidation treatment, Intensity change is shown by XPS analysis.Comparative Example 1 shows no peak near 287 eV, whereas Example 1 shows that a peak is formed around 287 eV, indicating that carbon nanotubes are oxidized.

12 is a Stress-Strain characteristic according to a preferred embodiment of the present invention. Referring to FIG. 12, it shows the degree of stretching when a film-type carbon oxide nanotube composite is applied as an electrode.

That is to say, in the case of Comparative Example 1 using carbon nanotubes not subjected to oxidation treatment, when a force of more than a certain strength is applied, it breaks, whereas in Examples 1 to 4, it shows a certain degree of elasticity. Is confirmed.

The above description is merely illustrative of the technical idea of the present invention, and those of ordinary skill in the art to which the present invention pertains will be able to make various modifications and variations without departing from the essential characteristics of the present invention.

Therefore, the embodiments disclosed in the present invention are not intended to limit the technical idea of the present invention, but to explain the technical idea, and the scope of the technical idea of the present invention is not limited by these embodiments.

The scope of protection of the present invention should be interpreted by the claims, and all technical ideas within the scope equivalent thereto should be construed as being included in the scope of the present invention.

100: stretch super capacitor
120: anode
140: cathode
160: electrolyte
200: stretch micro super capacitor
220: substrate
240: anode
260: cathode
280: electrolyte

Claims (6)

An oxidation treatment step of oxidizing carbon nanotubes to form carbon oxide nanotubes; And
A method of manufacturing a carbon oxide nanotube composite for a flexible energy storage device comprising: a step of forming a paste-type carbon oxide nanotube composite by mixing a polymer and an electrolyte with the carbon oxide nanotube. The method of claim 1,
In the oxidation treatment step,
Sodium chlorate (NaClO ₃ ), sodium perchlorate (NaClO ₄ ), potassium chlorate (KClO ₃ ) and potassium perchlorate (KClO ₄ ) of any one or more oxidizing agents, fuming nitric acid, sulfuric acid in the carbon nanotubes Carbon oxide for a new energy storage device characterized in that oxidation treatment is performed by reacting one or more of a strong acid among (sulfuric acid), nitric acid, hydrochloric acid, phosphoric acid and hydrogen peroxide. Method for producing a tube composite. The method of claim 1,
Between the oxidation treatment step and the complexing step,
The carbon dioxide nanotubes are centrifuged to neutralize the pH to 7 to separate them into a supernatant and a precipitate, and then a centrifugation step of obtaining a paste-type carbon oxide nanotubes from the precipitate; elastic energy further comprising: Method for producing a carbon oxide nanotube composite for storage container. The method of claim 1,
After the complexing step,
A film forming step of forming the paste-type carbon oxide nanotube composite into a film-type carbon oxide nanotube composite having elasticity by a solvent casting method; of the carbon oxide nanotube composite for a stretchable energy storage device, characterized in that it further comprises Manufacturing method A carbon oxide nanotube composite for a stretchable energy storage device, characterized in that it has elasticity by being formed by mixing carbon oxide nanotubes, polymers and electrolytes formed by oxidation treatment of carbon nanotubes. Separator; And
Including; positive and negative electrodes disposed on both sides of the separator,
The anode and the cathode,
A flexible energy storage device comprising a carbon oxide nanotube composite, characterized in that it is formed by mixing carbon oxide nanotubes formed by oxidation treatment of carbon nanotubes, a polymer, and an electrolyte, thereby having elasticity.

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