KR20220073070A - Energy harvester comprising debundled carbonnanotube yarn and method of preparing same - Google Patents

Abstract

The present invention provides a first electrode including a debundling carbon nanotube yarn; a second electrode; and an electrolyte, wherein the debundled carbon nanotube yarn includes carbon nanotubes, and the carbon nanotubes are twisted with each other. The energy harvester of the present invention and its manufacturing method use debundled carbon nanotube yarns impregnated with ions in the carbon nanotube bundle, thereby maximizing the potential difference to improve the performance of the energy harvester, and have excellent cycle characteristics there is

Description

ENERGY HARVESTER COMPRISING DEBUNDLED CARBONNANOTUBE YARN AND METHOD OF PREPARING SAME TECHNICAL FIELD

The present invention relates to an energy harvester including debundled carbon nanotube yarns and a method for manufacturing the same, and more particularly, to debundled carbon nanotubes with improved energy harvester performance by using debundled carbon nanotube yarns. It relates to an energy harvester comprising a yarn and a method for manufacturing the same.

Energy harvesting (also referred to as energy harvesting, or energy harvesting, etc.) refers to a method or technology that collects external energy in a predetermined method and converts it into electrical energy. Also, an energy harvester refers to an electronic or mechanical device capable of performing such energy harvesting. For example, the energy harvester may use or store solar energy or kinetic energy of a human body by converting it into electric energy corresponding to the characteristics of the device.

The energy harvesting technology is spotlighted as an eco-friendly energy technology because it is possible to secure energy without using fossil fuel combustion or nuclear power generation. Also, recently, energy harvesting technology using various physical phenomena has been introduced. For example, a technology to obtain electrical energy using the temperature difference of an object (thermoelectric effect), a technology to obtain electrical energy by applying vibration to a piezoelectric element (piezoelectric effect), a technology to obtain electrical energy using solar heat, and A technique for obtaining electrical energy (triboelectric effect) by using/or generating static electricity by friction has been introduced.

Korean Patent Publication No. 10-2018-0013549 Korean Patent Publication No. 10-2020-0024255

An object of the present invention is to improve the performance of the energy harvester by maximizing the potential difference by using debundled carbon nanotube yarns impregnated with ions in the carbon nanotube bundle, and an energy harvester with excellent cycle characteristics and a method for manufacturing the same is to provide

Another object of the present invention is to provide an energy harvester that can be used in an industry or a wearable industry that requires electrical energy in an extreme environment, and a method for manufacturing the same.

According to an aspect of the present invention, a first electrode comprising a debundling (debundling) carbon nanotube yarn (yarn); a second electrode; and an electrolyte, wherein the debundled carbon nanotube yarns include carbon nanotubes, and the carbon nanotubes are twisted with each other, and an energy harvest is provided.

Also, the debundled carbon nanotube yarn may be a coil type debundled carbon nanotube yarn in which coiling is added to the twisting.

In addition, the debundling may be an intercalation of ions generated from the electrolyte into the carbon nanotube bundle including the carbon nanotubes.

In addition, the ions are Na ⁺ , K ⁺ , H ⁺ , Mg ²⁺ , Ca ²⁺ , Cl ^- , F ^- , Br ^- , I ^- , OH ^- , SO ₄ ^2- , PO ₄ ^3- , NO ₃ ^- and It may include one or more selected from the group consisting of combinations thereof.

In addition, the carbon nanotube may include a multi-wall carbon nanotube (MWNT).

In addition, the first electrode and the second electrode may form an electrochemical double layer on the surfaces of the first electrode and the second electrode, respectively.

In addition, the electrolyte may include at least one selected from the group consisting of HCl, H ₂ SO ₄ , HF, HBr, NaCl, KCl, NaOH, organic electrolyte, sweat, sea water, body fluid, and combinations thereof.

In addition, the electrolyte may include at least one selected from the group consisting of sweat, seawater, body fluids, and combinations thereof.

In addition, the second electrode is platinum, gold, silver, copper, palladium, nickel, indium, aluminum, iron, rhodium, ruthenium, osmium, cobalt, molybdenum, zinc, vanadium, tungsten, titanium, manganese, chromium, and alloys thereof. It may include one or more selected from the group consisting of.

Also, in the energy harvester, a potential difference may be induced between the first electrode and the second electrode by deforming the first electrode.

Also, the deformation may be a tensile deformation.

The transformation may also be to convert some or all of the coiling to the twisting.

Also, the deformation may increase the potential difference.

In addition, the energy harvester may further include an energy storage unit for storing electrical energy using the potential difference.

In addition, the energy harvester may be one in which a redox reaction does not occur.

In addition, the energy harvester may further include a third electrode serving as a reference electrode.

According to another aspect of the present invention, there is provided a wearable electronic device including the energy harvester.

According to another aspect of the present invention, (a) drawing a carbon nanotube sheet from a carbon nanotube forest (drawing); (b) immersing the carbon nanotube sheet and the second electrode in an electrolyte; and (c) debundled carbon nanotube yarns by twisting the carbon nanotube sheet while generating a potential difference between the carbon nanotube sheet immersed in the electrolyte and the second electrode. manufacturing a first electrode comprising; Including, wherein the debundled carbon nanotube yarn includes carbon nanotubes, and the carbon nanotubes are twisted with each other to form an energy harvester manufacturing method is provided.

In addition, the debundling in step (c) may be to charge the ions generated from the electrolyte by the potential difference and intercalate the ions into the bundle including the carbon nanotubes. have.

In addition, the method of manufacturing the energy harvester (d) further twisting the debundled carbon nanotube yarn to obtain a coil type debundled carbon nanotube yarn in which coiling is added to the twist. manufacturing; may further include.

The energy harvester of the present invention and its manufacturing method use debundled carbon nanotube yarns impregnated with ions in the carbon nanotube bundle, thereby maximizing the potential difference to improve the performance of the energy harvester, and have excellent cycle characteristics there is

In addition, the energy harvester and the method for manufacturing the same of the present invention have an effect that can be applied to an industry or a wearable industry that requires electrical energy in an extreme environment.

1 is a schematic diagram showing a method of manufacturing an energy harvester according to the present invention.
2 is a schematic diagram showing the structure of a three-electrode system including an energy harvester according to the present invention.
3 is a schematic diagram showing the structure of an energy harvester according to the present invention.
4 is a graph relating to cyclic voltammetry of the energy harvesters prepared according to Example 1 and Comparative Example 1. FIG.
5 is a comparison graph of peak voltage and peak power according to resistance of the energy harvester manufactured according to Example 1 and Comparative Example 1. FIG.
6A is a graph showing peak power, average power, and energy per cycle according to the cycle of the energy harvester manufactured according to Example 1, and FIG. 6A is a graph showing Comparative Example 1 It is a graph showing peak power according to time.
7 is a graph showing changes in electrochemical properties according to an applied voltage of the energy harvesters prepared according to Examples 1 to 3 and Comparative Example 1. Referring to FIG.
8 is a graph illustrating changes in energy harvester performance according to applied voltages of energy harvesters manufactured according to Examples 1 to 3 and Comparative Example 1. Referring to FIG.

Since the present invention can apply various transformations and can have various embodiments, specific embodiments are illustrated and described in detail in the detailed description. However, this is not intended to limit the present invention to specific embodiments, and should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention. In describing the present invention, if it is determined that a detailed description of a related known technology may obscure the gist of the present invention, the detailed description thereof will be omitted.

In addition, terms including ordinal numbers such as first, second, etc. to be used below may be used to describe various elements, but the elements are not limited by the terms. The above terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, a first component may be referred to as a second component, and similarly, a second component may also be referred to as a first component.

Also, when it is stated that a certain component is “on another component,” “formed on another component,” “located on another component,” or “stacked on another component,” the It may be formed, positioned, or laminated by being directly attached to the front surface or one surface on the surface of other components, but it will be understood that other components may be further present in the middle.

The singular expression includes the plural expression unless the context clearly dictates otherwise. In the present application, terms such as “comprise” or “have” are intended to designate that a feature, number, step, operation, component, part, or combination thereof described in the specification exists, but one or more other features It should be understood that this does not preclude the existence or addition of numbers, steps, operations, components, parts, or combinations thereof.

1 is a schematic diagram illustrating a method of manufacturing an energy harvester according to the present invention, and FIG. 2 is a schematic diagram illustrating a structure of a three-electrode system including an energy harvester according to the present invention. Hereinafter, an energy harvester of the present invention and a manufacturing method thereof will be described with reference to FIGS. 1 and 2 .

The present invention provides a first electrode including a debundling carbon nanotube yarn; a second electrode; and an electrolyte, wherein the debundled carbon nanotube yarn includes carbon nanotubes, and provides an energy harvester in which the carbon nanotubes are twisted with each other.

The debundled carbon nanotube yarn may be a coil type debundled carbon nanotube yarn in which coiling is added to the twisting.

The debundling may be an intercalation of ions generated from the electrolyte into the carbon nanotube bundle including the carbon nanotubes.

The ions are Na ⁺ , K ⁺ , H ⁺ , Mg ²⁺ , Ca ²⁺ , Cl ^- , F ^- , Br ^- , I ^- , OH ^- , SO ₄ ^2- , PO ₄ ^3- , NO ₃ ^- and these It may include one or more selected from the group consisting of a combination of.

The carbon nanotube may include a multi-wall carbon nanotube (MWNT).

The multi-wall carbon nanotube (MWNT) may have a diameter of 1 nm to 20 nm, preferably 5 nm to 15 nm, and more preferably 7 nm to 10 nm.

If the diameter of the multi-walled carbon nanotube (MWNT) is less than 1 nm, it is difficult to manufacture, and if it exceeds 20 nm, the performance of the energy harvester is remarkably deteriorated, which is not preferable for use.

The first electrode and the second electrode may form an electrochemical double layer on surfaces of the first electrode and the second electrode, respectively.

The electrolyte may include at least one selected from the group consisting of HCl, H ₂ SO ₄ , HF, HBr, NaCl, KCl, NaOH, organic electrolyte, sweat, sea water, body fluid, and combinations thereof, and the organic electrolyte is As cations, tetraethylammonium (TEA ⁺ ), tetrabutylammonium (TBA ⁺ ), tetrahexylammonium (THA ⁺ ), 1-ethyl-3-methyl-imidazolium (EMI ⁺ ), 1-butyl-3-methyl are Midazolium (BMI ⁺ ) is used, and tetrafluoroborate (BF ₄ ^- ), hexafluorophosphate (PF ₆ ^- ), bis(trifluoromethanesulfonyl)imide (TFSI ^- ) is used as an anion. It may contain an electrolyte.

The electrolyte may include at least one selected from the group consisting of sweat, seawater, body fluids, and combinations thereof.

The concentration of the electrolyte may be 0.01M to 5M, preferably 0.05M to 1M.

The second electrode is made of platinum, gold, silver, copper, palladium, nickel, indium, aluminum, iron, rhodium, ruthenium, osmium, cobalt, molybdenum, zinc, vanadium, tungsten, titanium, manganese, chromium, and alloys thereof. It may include one or more selected from the group consisting of, and preferably includes platinum.

In the energy harvester, a potential difference may be induced between the first electrode and the second electrode by deforming the first electrode.

The deformation may be a tensile deformation.

The transformation may be to convert some or all of the coiling to the twisting.

The deformation may increase the potential difference.

The energy harvester may further include an energy storage unit for storing electrical energy using the potential difference.

The energy harvester may be one in which a redox reaction does not occur.

The energy harvester may further include a third electrode serving as a reference electrode.

Referring to FIG. 2 , a debundling carbon nanotube yarn is used as a working electrode, pt mesh/CNT buckypaper having a high specific surface area is used as a counter electrode, and Ag/AgCl is used as a water-soluble standard electrode. and can constitute an electrochemical cell of a three-electrode or two-electrode system in which the working electrode, the counter electrode, and the standard electrode are immersed in an electrolyte. When mechanical tensile strain is applied to the working electrode in the system, electrical energy is generated due to a change in the capacitance inside the working electrode.

In the debundled carbon nanotube yarn, as ions generated from the electrolyte are intercalated into the carbon nanotube bundle, bundling than the carbon nanotube yarn (conventional electrode) in which ions are not impregnated. As the degree of decrease decreases, the internal structure changes, which results in a larger capacitance of the electrode in an untensioned state (strain = 0%). In addition, when the same mechanical deformation is applied, the change in the electrochemical capacitance is large, and the potential difference generated accordingly is large, and a higher electrical power is generated compared to the conventional electrode. In addition, the debundled carbon nanotube yarn can maintain harvester performance without creep even after repeated mechanical deformation over 1000 times.

The present invention also provides a wearable electronic device including an energy harvester.

In addition, the present invention comprises the steps of (a) drawing a carbon nanotube sheet from a carbon nanotube forest; (b) immersing the carbon nanotube sheet and the second electrode in an electrolyte; and (c) debundled carbon nanotube yarns by twisting the carbon nanotube sheet while generating a potential difference between the carbon nanotube sheet immersed in the electrolyte and the second electrode. manufacturing a first electrode comprising; Including, wherein the debundled carbon nanotube yarn includes carbon nanotubes, and provides a method for manufacturing an energy harvester in which the carbon nanotubes are twisted with each other.

The debundling in step (c) may be to charge ions generated from the electrolyte by the potential difference and intercalate the ions into the bundle including the carbon nanotubes. .

In step (c), a voltage may be applied to the electrolyte to generate a potential difference between the carbon nanotube sheet and the second electrode.

The voltage may be -0.01V to -1.0V, preferably -0.05V to -0.8V, and more preferably -0.1V to -0.7V.

When the voltage is less than -0.01V, the amount of charge used for debundling of the carbon nanotube yarn is small, which is not preferable, and when it exceeds -1.0V, the performance of the energy harvester decreases because the capacitance change ratio decreases. It is not desirable to become

Also, as the degree of debundling increases, capacitance may increase.

In the method of manufacturing the energy harvester, after step (c), the debundled carbon nanotube yarn is further twisted by twisting the coil type debundled carbon nano It may further include; (d) for producing a tube yarn.

[Example]

Hereinafter, the present invention will be described in more detail by way of examples. However, this is for illustrative purposes, and the scope of the present invention is not limited thereto.

[Production of energy harvester including debundled carbon nanotube yarn (d-CNT yarn)]

Example 1

Platinum mesh (Pt mesh)/CNT buckypaper having a mesh size of 1 mm in width and 1 mm in length was used as a counter electrode.

Also, referring to FIG. 1, first, a multi-walled carbon nanotube sheet (MWNT sheet, density: 1.7 ug/cm ² ) is pulled from a multi-walled carbon nanotube forest (spinnable MWNT forest) and overlapped three times, and the multi-walled carbon nanotube The sheet and the counter electrode were immersed in 0.1M HCl electrolyte to prepare a two-electrode system. Next, while applying a -0.2V voltage between the multi-walled carbon nanotube sheet and the counter electrode, one end of the multi-walled carbon nanotube sheet is collected, a weight of 5 g is weighed, and 5 at a rate of about 120 times per minute. By twisting for minutes, a coil type debundled carbon nanotube yarn having a diameter of 8.2 nm was prepared, and the coil type debundled carbon nanotube yarn was used as a working electrode. Finally, an energy harvester having the structure of FIG. 3 was manufactured.

Example 2

An energy harvester was manufactured in the same manner as in Example 1, except for applying a -0.4V voltage instead of applying a -0.2V voltage in Example 1.

Example 3

An energy harvester was manufactured in the same manner as in Example 1, except for applying a -0.6V voltage instead of applying a -0.2V voltage in Example 1.

[Production of energy harvester including carbon nanotube yarn (bare CNT yarn)]

Comparative Example 1

Platinum mesh (Pt mesh)/CNT buckypaper having a mesh size of 1 mm in width and 1 mm in length was used as a counter electrode.

In addition, first, a multi-walled carbon nanotube sheet (MWNT sheet) is pulled out from a multi-walled carbon nanotube forest (spinnable MWNT forest), one end of the multi-walled carbon nanotube sheet is collected, a weight of 5 g is added, and 120 times per minute. A coiled CNT yarn was prepared by twisting at a speed for 5 minutes, and the coiled CNT yarn was used as a working electrode.

Then, the counter electrode and the working electrode were immersed in 0.1M HCl electrolyte, and the counter electrode and the working electrode were connected to each other to prepare an energy harvester.

[Test Example]

Test Example 1: Cyclic voltammetry analysis

4 is a graph relating to cyclic voltammetry of the energy harvesters prepared according to Example 1 and Comparative Example 1. FIG.

According to FIG. 4, as compared with Comparative Example 1 including bare CNT, Example 1 including d-CNT yarn had a capacitance of about 11.9% from 4.2 F/g to 4.7 F/g at 0% strain. showed an increasing trend. In addition, when 30% strain was applied, the change rate of capacitance was 38.7%, which showed an increased tendency compared to Comparative Example 1. This is due to the intercalation of ions into the CNT bundle in the process of making the coil structure, debundling the carbon nanotube bundle, and increasing the effective surface area to increase the static electricity measured by weight It is considered that the gravimetric capacitance has increased.

Test Example 2: Analysis of resistance characteristics

5 is a comparison graph of peak voltage and peak power according to resistance of the energy harvester manufactured according to Example 1 and Comparative Example 1. FIG.

Referring to FIG. 5 , it was confirmed that both of the energy harvesters manufactured according to Example 1 and Comparative Example 1 performed impedance matching at 400 ohm and exhibited the highest peak power. Example 1 exhibited an improved peak power (peak power) than Comparative Example 1 at 43.1 W/kg. This increase in harvesting performance seems to be due to an increase in the potential difference (dV) due to an increase in capacitance change based on the Q=CV formula.

Test Example 3: Cycle Characterization

6A and 6B are graphs analyzing characteristics according to cycles of energy harvesters manufactured according to Example 1 and Comparative Example 1, and peak power under an impedance matching resistance of 400 ohm and 1 Hz sinusoidal strain. , average power, and energy per cycle. Average power was calculated according to Equation 1 below.

[Equation 1]

(R: impedance, V(t): Generated voltage)

(R: impedance, V(t): Generated voltage)

6A and 6B, it was confirmed that the performance of the energy harvester manufactured according to Example 3 was maintained without creep even when mechanical strain of 30% was repeatedly applied for 1000 cycles. The peak power of Example 1 prepared by applying -0.2V was 43.1 W/kg, and a value increased by 5% compared to Comparative Example 1 was obtained.

Test Example 4: Analysis of changes in electrochemical properties according to applied voltage

7 is a graph showing changes in electrochemical properties according to an applied voltage of the energy harvesters prepared according to Examples 1 to 3 and Comparative Example 1. Referring to FIG.

Referring to FIG. 7 , an appropriate applied voltage required to make the debundling carbon nanotube yarn was found.

Test Example 5: Analysis of energy harvester performance change according to applied voltage

8 is a graph illustrating changes in energy harvester performance according to applied voltages of energy harvesters manufactured according to Examples 1 to 3 and Comparative Example 1. Referring to FIG.

Referring to FIG. 8 , in the case of Examples 2 and 3 manufactured under a voltage greater than -0.2V, it was confirmed that the performance was deteriorated because the capacitance change ratio was rather decreased. Therefore, it can be seen that the performance of the energy harvest according to Example 1 prepared under a voltage of -0.2V is the most optimized.

As mentioned above, although preferred embodiments of the present invention have been described, those of ordinary skill in the art can add, change, delete or The present invention may be variously modified and changed by addition, etc., and this will also be included within the scope of the present invention. For example, each component described as a single type may be implemented in a dispersed form, and likewise components described as distributed may also be implemented in a combined form. The scope of the present invention is indicated by the following claims rather than the above detailed description, and all changes or modifications derived from the meaning and scope of the claims and their equivalent concepts should be interpreted as being included in the scope of the present invention. do.

Claims (20)

A first electrode including a debundling (debundling) carbon nanotube yarn (yarn);
a second electrode; and
electrolyte; including;
The debundled carbon nanotube yarn includes carbon nanotubes, and the carbon nanotubes are twisted to form an energy harvester. According to claim 1,
The debundled carbon nanotube yarn is a coil type debundled carbon nanotube yarn in which a coiling is added to the twisting energy harvester. According to claim 1,
The debundling is an energy harvester, characterized in that the ions (ions) generated from the electrolyte are intercalated into the carbon nanotube bundle including the carbon nanotubes. 4. The method of claim 3,
The ions are Na ⁺ , K ⁺ , H ⁺ , Mg ²⁺ , Ca ²⁺ , Cl ^- , F ^- , Br ^- , I ^- , OH ^- , SO ₄ ^2- , PO ₄ ^3- , NO ₃ ^- and these An energy harvester comprising at least one selected from the group consisting of a combination of The method of claim 1,
The energy harvester, characterized in that the carbon nanotube comprises a multi-wall carbon nanotube (MWNT). According to claim 1,
wherein the first electrode and the second electrode form an electrochemical double layer on the surfaces of the first electrode and the second electrode, respectively. According to claim 1,
The electrolyte comprises at least one selected from the group consisting of HCl, H ₂ SO ₄ , HF, HBr, NaCl, KCl, NaOH, organic electrolyte, sweat, seawater, body fluid, and combinations thereof. 8. The method of claim 7,
The energy harvester, characterized in that the electrolyte comprises at least one selected from the group consisting of sweat, sea water, body fluids and combinations thereof. The method of claim 1,
The second electrode is made of platinum, gold, silver, copper, palladium, nickel, indium, aluminum, iron, rhodium, ruthenium, osmium, cobalt, molybdenum, zinc, vanadium, tungsten, titanium, manganese, chromium, and alloys thereof. An energy harvester comprising at least one selected from the group consisting of. The method of claim 1,
In the energy harvester, a potential difference is induced between the first electrode and the second electrode by deforming the first electrode. 11. The method of claim 10,
The energy harvester, characterized in that the deformation is a tensile deformation (tensile deformation). 11. The method of claim 10,
wherein said deformation converts some or all of said coiling into said twisting. 13. The method of claim 12,
wherein said deformation increases said potential difference. 11. The method of claim 10,
The energy harvester, characterized in that the energy harvester further comprises an energy storage unit for storing electrical energy using the potential difference. The method of claim 1,
The energy harvester is an energy harvester, characterized in that the redox reaction (redox reaction) does not occur. According to claim 1,
The energy harvester, characterized in that the energy harvester further comprises a third electrode that is a reference electrode (reference electrode). A wearable electronic device comprising the energy harvester according to claim 1 . (a) drawing a carbon nanotube sheet from a carbon nanotube forest;
(b) immersing the carbon nanotube sheet and the second electrode in an electrolyte; and
(c) carbon nanotube yarn debundled by twisting the carbon nanotube sheet while generating a potential difference between the carbon nanotube sheet immersed in the electrolyte and the second electrode; manufacturing a first electrode to including,
The debundled carbon nanotube yarn includes carbon nanotubes, and the carbon nanotubes are twisted with each other. 19. The method of claim 18,
The debundling in step (c) is characterized in that by charging the ions generated from the electrolyte by the potential difference, the ions are intercalated into the bundle including the carbon nanotubes. A method for manufacturing an energy harvester. 19. The method of claim 18,
The method of manufacturing the energy harvester is
(d) further twisting the debundled carbon nanotube yarn to prepare a coil-type debundled carbon nanotube yarn in which coiling is added to the twist; Method of manufacturing an energy harvester, characterized in that it further comprises.

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