KR20180029629A - Triboelectric device using ferroelectric material - Google Patents

Abstract

The present invention relates to a triboelectric device using a ferroelectric material. According to the present invention, the triboelectric device using a ferroelectric comprises: a lower electrode layer; a ferroelectric layer located on an upper part of the lower electrode layer, and made of a ferroelectric material; a triboelectric charge layer located on an upper part of the ferroelectric layer; and an upper electrode layer separated from an upper part of the triboelectric charge layer. Triboelectricity is generated as the triboelectric charge layer and the upper electrode layer are separated from each other after being contacted by an external force. According to the present invention, the triboelectric device significantly reduces a degree of wear of the triboelectric device by using the ferroelectric material, thereby increasing generation efficiency as well as durability of the device.

Description

[0001] Triboelectric device using ferroelectric material [0002]

Field of the Invention [0002] The present invention relates to a triboelectric device using a ferroelectric substance, and more particularly, to a triboelectric device using a ferroelectric material capable of enhancing the durability and efficiency of the triboelectric device.

Research on renewable energy is actively underway due to environmental problems such as rapid decrease of fossil fuels such as coal / oil and global warming. Among them, friction energy utilizes the energy generated by the difference of electric charge caused by static electricity generated when two different materials come into contact with each other.

Unlike conventional solar energy, wind energy, fuel cell, etc., frictional power generation can extract infinite mechanical energy of consuming generated from human vibrations or human vibrations, Energy generation method.

The triboelectric power plant produces electrons by inducing electrostatic induction by moving electrons by rubbing a substance having a large property of emitting electrons and a substance having a large property of accepting electrons when friction occurs. In the past, researches have been conducted mainly on making power generation devices using materials having a large difference in electrical properties and increasing efficiency.

The energy conversion method using the electrostatic characteristic is considered to be a highly effective technology that can lead to a breakthrough of technology through convergence with nanotechnology which can be made compact and lightweight with high conversion efficiency. For example, in recent years, mobile devices have been widely used and wearable devices worn on the body have been rapidly emerging, and a great deal of attention has been focused on them as power generation devices for supplying or charging these devices.

Since triboelectric devices basically generate electricity by contact of two different objects, there is a phenomenon that two objects are severely worn out for a long period of use, resulting in various durability problems. As an attempt to solve this problem, there has been reported a method of applying heat to a worn polymer by using a shape memory polymer, and a method of modifying both the surface and the inside of a polymer by using an atomic layer deposition method.

However, since the method of modifying a worn device by using a subsequent process such as heating or vapor deposition requires a great deal of time and cost, there is a need for a technique capable of fundamentally reducing the degree of wear of the device itself.

The technology to be a background of the present invention is disclosed in Korean Patent No. 0949146 (published on Mar. 25, 2010).

An object of the present invention is to provide a triboelectric device using a ferroelectric material capable of enhancing the durability and power generation efficiency of a triboelectric device by inserting a ferroelectric below the triboelectric charge layer.

The present invention relates to a ferroelectric capacitor comprising a lower electrode layer, a ferroelectric layer disposed on the upper electrode layer and formed of a ferroelectric material, a triboelectrification layer disposed on the ferroelectric layer, The present invention provides a triboelectric device using a ferroelectric material in which triboelectricity is generated as the triboelectrification layer and the upper electrode layer are separated from each other after being contacted by an external force.

Here, the charge of the upper electrode layer moves to the triboelectrification layer according to the contact, the triboelectric charge layer is negatively charged, and the upper electrode layer is positively charged, and the ferroelectric layer has a positive charge and a negative charge, respectively And may have a structure that is polarized at the upper and lower positions.

Also, the triboelectric charging layer may include at least one of PDMS, PTFE, PMMA, and PI, and the ferroelectric layer may include PVDF or P (VDF-TrFE).

Further, the triboelectrification layer may have a thickness of 10 to 18 占 퐉.

More preferably, the triboelectrification layer may have a thickness of 13 mu m.

According to the triboelectric device using ferroelectric according to the present invention, the degree of wear of the triboelectric device can be drastically reduced by using the ferroelectric material, thereby enhancing the durability of the device as well as the power generation efficiency.

Further, according to the present invention, since the negative charge induced in the triboelectrification layer due to contact with the electrode layer can be fixed without being lost by the positive charge of the ferroelectric, and the negative charge of the triboelectric charge layer can be maintained considerably even when the contact is dropped, And the durability of the device can be increased.

Further, during the contact process between the triboelectrification layer and the electrode layer, a negative charge can be induced more quickly and more in the triboelectrification layer due to the positive charge of the ferroelectric substance, so that a larger current can be output in a short time, There is an advantage.

1 is a view illustrating a triboelectric device using a ferroelectric substance according to an embodiment of the present invention.
Fig. 2 is a view showing a driving principle of the triboelectric device shown in Fig. 1. Fig.
3 is a graph comparing current intensities before and after ferroelectric inserting in the embodiment of the present invention.
FIG. 4 is a graph comparing the amount of charge induced in the triboelectric charging layer before and after inserting the ferroelectric in the embodiment of the present invention.
FIG. 5 is a graph comparing magnitudes of voltage and current before and after inserting a ferroelectric in the embodiment of the present invention. FIG.
FIG. 6 is a graph comparing current intensities generated according to the distance between the electrodes and the polymer before and after the ferroelectric material is inserted in the embodiment of the present invention.
FIG. 7 shows the results of comparing the magnitude of the current value according to the thickness of the triboelectrification layer in the embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention.

1 is a view illustrating a triboelectric device using a ferroelectric substance according to an embodiment of the present invention. Referring to FIG. 1, a triboelectric device 100 according to an embodiment of the present invention includes a lower electrode layer 110, a ferroelectric layer 120, a triboelectrification layer 130, and an upper electrode layer 140.

The lower electrode layer 110 and the upper electrode layer 140 include a conductive material. The lower electrode layer 110 and the upper electrode layer 140 may be formed in a form having transparency. For example, each of the electrode layers 110 and 140 may be formed of ITO or Al, or may be formed of ITO or Al deposited on a transparent film.

The lower electrode layer 110 and the upper electrode layer 140 may be electrically connected to both ends of the storage device 10 such as a capacitor through an electric circuit including a line to store electricity produced by charging.

The ferroelectric layer 120 is disposed between the lower electrode layer 110 and the triboelectrification layer 130 and is formed of a ferroelectric material. Specifically, the ferroelectric layer 120 may be formed of PVDF or P (VDF-TrFE) material.

The ferroelectric material has a structure in which electrical dipoles (dipoles) are aligned as a material having spontaneous polarization. Spontaneous polarization means that the center of positive charge and negative charge are separated so that one side of the crystal is charged positively and the other side is negatively charged. As shown in FIG. 1, in the embodiment of the present invention, the ferroelectric layer 120 has a structure in which positive and negative charges are polarized at upper and lower positions, respectively.

The triboelectrification layer 130 is disposed on the upper part of the ferroelectric layer 120 and the upper electrode layer 140 is disposed on the upper part of the triboelectrification layer 130. The triboelectrification occurs between the triboelectrification layer 130 and the upper electrode layer 140 and is generated according to the relative positions of the triboelectrification layer 130 and the upper electrode layer 140.

The triboelectric charge layer 130 is formed of a material that easily accepts electrons during rubbing, and the upper electrode layer 140 is formed of a material that allows relatively easy electrons to be emitted. Accordingly, the triboelectric charging layer 130 is charged with (-) and the upper electrode layer 140 is charged with (+) at the time of rubbing.

In an embodiment of the present invention, the triboelectric charge layer 130 may include at least one material selected from the group consisting of polydimethylsiloxane (PDMS), polytetrafluoroethylene (PTFE), polymethylmethacrylate (PMMA), and polyimide (PI). The triboelectrification layer 130 has a thickness of 10 to 18 mu m, and may preferably have a thickness of 13 mu m.

The upper electrode layer 140 is vertically lowered by an external force and is contactable with the upper electrode layer 140. After the contact, the upper electrode layer 140 is lifted and separated. Here, the external force is 30 N, the vertical movement distance of the upper electrode layer 140 is 4 cm, the temperature of the friction power generation environment is 23.5 ° C, and the humidity is 13%.

Fig. 2 is a view showing a driving principle of the triboelectric device shown in Fig. 1. Fig.

As shown in FIG. 2, in the present embodiment, triboelectricity is generated as the triboelectrification layer 130 and the upper electrode layer 140 are separated from each other after being contacted by an external force. That is, in the process of the triboelectric charge layer 130 and the upper electrode layer 140 adhering to each other, electricity is generated by the potential difference between both electrodes.

Specifically, the charge of the upper electrode layer 140 is moved to the tribo charging layer 130 by the contact between the triboelectric charge layer 130 and the upper electrode layer 140, the tribo charging layer 130 is negatively charged, (140) is charged to (+). For example, when the triboelectric charge layer 130 is made of PDMS and the upper electrode layer 140 is made of ITO, the triboelectric charge layer 130 is negatively charged by the charging heat during friction and the upper electrode layer 140 is charged by +), Respectively.

As shown in FIG. 2, a ferroelectric layer 120 is disposed under the triboelectrification layer 130, and positive charges are polarized on the upper surface of the ferroelectric layer 120. Therefore, the negative charges charged in the triboelectric charge layer 130 can be maintained without disappearance by the attractive force of the positive charges of the ferroelectric layer 120.

In addition, since the negative charge can be maintained for a longer time even when the tribo charging layer 130 is in contact with the upper electrode layer 140 for a longer time, it is possible to effectively produce electricity even with a low number of contact, To reduce device wear and improve durability.

3 is a graph comparing current intensities before and after ferroelectric inserting in the embodiment of the present invention. Fig. 3 (a) shows a case where no ferroelectric is inserted, and Fig. 3 (b) shows a case where a ferroelectric is inserted as in the embodiment of the present invention.

The graph of Fig. 3 is a current graph observed in a triboelectric device, in which a current value is measured repeatedly in positive and negative. This pattern is related to the switching of the current direction when the triboelectrification layer 130 and the upper electrode layer 140 are brought closer to and away from each other. It can be seen from the results of FIG. 3 that more negative charges are induced on the triboelectric charging layer 130 than when the ferroelectric is not inserted at the time of inserting the ferroelectric.

In the case of the ammeter connected between the electrode layers in FIG. 3, it means that the electric current intensity is higher as the electric current instruction is inclined more than the initial vertical state. Of course, the greater the current strength, the greater the electricity production capacity. Comparing the two cases, it can be seen that the current intensity is increased in the case of (b) in which the ferroelectric layer 120 is inserted (a).

FIG. 4 is a graph comparing the amount of charge induced in the triboelectric charging layer before and after inserting the ferroelectric in the embodiment of the present invention. 4 (a) shows a case where no ferroelectric is inserted, and FIG. 4 (b) shows a case where a ferroelectric is inserted as in the embodiment of the present invention.

From the results of FIG. 4, it was found that the current intensity was measured at about 3 μA in the case of (a) without ferroelectric, while it was measured at 12 μA in case of (b) .

3 and 4, negative charge can be induced more quickly and more in the triboelectric charge layer 130 at the time of friction between the charge layer and the electrode layer in accordance with the positive charge of the ferroelectric layer 120, It can be seen that more electricity can be produced in a shorter time than in the case of inserting, and the power generation efficiency can be increased.

FIG. 5 is a graph comparing magnitudes of voltage and current before and after inserting a ferroelectric in the embodiment of the present invention. FIG. The blue color graph represents the case where no ferroelectric material is inserted, and the red color represents the case where the ferroelectric material is inserted. The left data shows a case where the contact between the triboelectrification layer 130 and the upper electrode layer 140 is repeated continuously for 1 hour, and the right data shows a case where the contact is stopped after that.

5, when the ferroelectric material is inserted, the current value reaches the maximum value after about 15 minutes and the voltage value reaches the maximum value. After about 30 minutes, when the ferroelectric material is not inserted, about 50 minutes Can be obtained.

In addition, when the contact is stopped, it can be confirmed that the charge is maintained for a much longer period of time in the ferroelectric inserted device. Therefore, according to the embodiment of the present invention, since the negative charge can be maintained for a longer time even when the contact is released, the number of contact can be reduced and the durability of the device can be further increased.

FIG. 6 is a graph comparing current intensities generated according to distances between electrodes and a polymer before and after insertion of a ferroelectric material in an embodiment of the present invention. Here, the electrode and the polymer represent the upper electrode layer 140 and the triboelectrification layer 130, respectively.

The upper drawing shows the case where the ferroelectric is not inserted, and the lower drawing shows the result when the ferroelectric is inserted. The abscissa of the graph indicates the time and the ordinate indicates the current value. The change in the current value is observed while changing the z value.

6 shows a current measurement result when the operation of moving the upper electrode layer 140 by z value and then returning to z = 0 is repeated using each z value. The scales of the current values for the two cases are different. This is because the current value is measured much larger under the same conditions at the time of ferroelectric inserting.

In Figure 6, z means the distance from which the top electrode layer 140 descends from its original position (z = 0). Since the distance between the upper electrode layer 140 and the frictional electrification layer 130 is 4 cm, the upper electrode layer 140 and the frictional electrification layer 130 contact each other when the descending length z is 4 cm. Respectively.

As the z value decreases, the intensity of the current decreases, which is a phenomenon commonly seen in friction generating devices. When a ferroelectric material is inserted, a larger current peak can be seen when the z value is small, which indicates that the current can flow even when the electrode does not touch the polymer directly but comes close.

FIG. 7 shows the results of comparing the magnitude of the current value according to the thickness of the triboelectrification layer in the embodiment of the present invention. FIG. 7 shows that the PDMS material is used as the triboelectrification layer, and the magnitude of the output current varies depending on the thickness of the PDMS. Particularly, when the PDMS thickness is 10 to 18 탆, the performance is excellent, and 13 탆 showing the maximum current peak is the optimum thickness.

As described above, according to the triboelectric device using the ferroelectric material according to the present invention, the degree of wear of the triboelectric device can be remarkably reduced by using the ferroelectric material, thereby enhancing the durability of the device as well as the power generation efficiency.

Further, according to the present invention, since the negative charge induced in the triboelectric charging layer by contact with the electrode layer can be fixed without being vanished by the positive charge of the ferroelectric, and the negative charge of the triboelectric charging layer can be maintained substantially even when the contact is dropped, The number of times can be drastically reduced and the durability of the device can be increased.

Further, during the contact process between the triboelectrification layer and the electrode layer, a negative charge can be induced more quickly and more in the triboelectrification layer due to the positive charge of the ferroelectric layer, so that a larger current can be output in a short time, .

While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. Accordingly, the true scope of the present invention should be determined by the technical idea of the appended claims.

100: Triboelectric device 110: Lower electrode layer
120: ferroelectric layer 130: triboelectric charge layer
140: upper electrode layer

Claims (5)

A lower electrode layer;
A ferroelectric layer disposed on the lower electrode layer and formed of a ferroelectric material;
A triboelectric charge layer disposed on the ferroelectric layer; And
And an upper electrode layer disposed on an upper portion of the triboelectrification layer,
Wherein the triboelectric layer and the upper electrode layer are brought into contact with each other by an external force and are spaced apart from each other, thereby generating triboelectricity. The method according to claim 1,
The charge of the upper electrode layer moves to the triboelectrification layer according to the contact, the tribocharge layer is negatively charged, the upper electrode layer is charged positively,
The ferroelectric layer may include,
A triboelectric device using a ferroelectric having a structure in which positive and negative charges are polarized at upper and lower positions, respectively. The method according to claim 1,
Wherein the ferroelectric layer is formed of at least one material selected from the group consisting of PDMS, PTFE, PMMA and PI, and the ferroelectric layer is formed of PVDF or P (VDF-TrFE) material. The method according to any one of claims 1 to 3,
Wherein the triboelectrification layer is a ferroelectric having a thickness of 10 to 18 mu m. The method of claim 4,
Wherein the triboelectric charge layer has a thickness of 13 占 퐉.

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