KR20120118269A - Energy harvesting system using elastic body covered ferroelectricity fabricated dip coating method - Google Patents

Abstract

PURPOSE: An energy gaining system and a manufacturing method thereof are provided to convert external pressure or mechanical vibration into an electric energy. CONSTITUTION: A conductive spiral core electrode(401) has elastic force or elasticity. A ferroelectric polymer layer(402) is selectively formed on a surface of a center electrode. A surface electrode(403) is formed on a surface of the ferroelectric polymer layer. The center electrode includes Fe, Ni, Cr, Ti, Mo, Ag, Au, Al, Cu, W, or TiN.

Description

Energy harvesting system using piezoelectric element made of elastomer and its manufacturing method {Energy Harvesting System Using Elastic Body Covered Ferroelectricity Fabricated Dip Coating Method}

The present invention relates to a piezoelectric element and a method of manufacturing the same, and more particularly, an energy harvesting system using a piezoelectric element in which a ferroelectric polymer layer and a surface electrode are formed on a spiral core electrode having a resilient force or elasticity. It relates to a manufacturing method.

In general, a piezoelectric element is a device that uses a piezoelectric effect in which an internal polarization is induced in proportion to the pressure when an external pressure is applied, and a mechanical deformation occurs due to an external electric field to generate a current, and mainly consists of a film structure. This piezoelectric element mutually converts mechanical vibration energy and electrical energy.

However, the piezoelectric element of the film structure is not easy to be deformed due to its morphological characteristics, so the application range is limited, and the mechanical toughness due to external pressure is weak. In addition, the surface area receiving the pressure is narrow, the efficiency is low in energy generation and conversion, and the displacement generated by the pressure is small. In addition, a general piezoelectric element manufacturing method has a disadvantage in that it is difficult to manufacture a variety of piezoelectric elements, and the cost burden in the manufacturing process is high.

The present invention is to solve the above-described problems, piezoelectric elements made of an elastic body capable of converting the external pressure or mechanical vibration of the front and rear, front and rear directions into electrical energy, and increases the current and voltage generated per unit area and unit pressure And its manufacturing method.

Furthermore, an object of the present invention is to provide a piezoelectric element having a strong mechanical toughness against external pressure and having elasticity or elasticity applicable to a wide range of fields, and at the same time to provide a piezoelectric element having various structures.

Energy harvesting system using a piezoelectric element made of an elastic body according to an embodiment of the present invention for achieving this object is selectively on the surface of the spiral core electrode (Core Electrode), the core electrode (Core Electrode) having an elastic force or elasticity It characterized in that it comprises a surface electrode (Surface Electrode) formed on the surface of the formed ferroelectric polymer (Ferroelectric Polymer) layer and the ferroelectric polymer (Ferroelectric Polymer) layer.

In addition, the center electrode is formed of various structures such as a spring, a string, a ball, or a bar, and has an elastic force or elasticity. The ferroelectric polymer layer is made of a piezoelectric polymer such as PVDF and P (VDF-TrFE), P (VDF-TrFE-CFE) or P (VDF-HFP) which is a copolymer of PVDF. do. The surface electrode is made of a conductive polymer such as polyaniline, polypyrrole or PPs.

Furthermore, the method of manufacturing an energy harvesting system using a piezoelectric element made of an elastic body may include preparing a conductive center electrode, and selectively forming a ferroelectric polymer layer by a dip coating method on the surface of the center electrode. Step, drying and heat-treating the center electrode on which the ferroelectric polymer layer is formed, forming a surface electrode on the surface of the ferroelectric polymer layer to create a piezoelectric element and permanently inside the piezoelectric element by high voltage polling process It characterized in that it comprises the step of aligning the dipole (Permanent Dipole) in one direction.

As described above, according to the present invention, the ferroelectric polymer layer and the surface electrode are sequentially formed on the spiral core electrode having elastic force or elasticity, thereby providing a vertical, horizontal, vertical direction. External pressure or mechanical vibrations can be converted into electrical energy.

Further, by manufacturing the energy harvesting system using the piezoelectric element made of an elastic body according to the present invention by a dip coating method, it is possible to manufacture a piezoelectric element of a complex structure, it is possible to simplify the manufacturing process. Therefore, various sizes and shapes of devices such as ship propellers and aircraft propellers may be utilized as piezoelectric elements.

Furthermore, by providing a spring piezoelectric element of helical structure, the surface area of the piezoelectric element is widened, and the magnitude of displacement caused by external pressure is increased, thereby increasing the current and voltage generated per unit area. Therefore, it is possible to improve the energy generation efficiency, and easy energy conversion has a useful effect that can be utilized in suspension of vehicles and motorcycles, bridges connected with a plurality of strings (String).

1 is a cross-sectional view illustrating a general piezoelectric element.
2 is a conceptual diagram illustrating the piezoelectric effect of the piezoelectric element.
3 is a conceptual diagram illustrating another piezoelectric effect of the piezoelectric element.
4 is a view illustrating an energy harvesting system according to an embodiment of the present invention.
5 is a view for explaining an energy harvesting system according to another embodiment of the present invention.
6 is a flowchart illustrating a method of manufacturing an energy harvesting system according to an embodiment of the present invention.
7 is a view for explaining a dip coating apparatus according to an embodiment of the present invention.
8 is a photograph of an energy harvesting system and a piezoelectric element according to the prior art according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout.

1 is a cross-sectional view illustrating a general piezoelectric element. As shown, the piezoelectric element 100 includes a plate-shaped ceramic substrate 101 and a piezoelectric electrode 102 formed on the ceramic substrate 101.

In one embodiment, the ceramic substrate 101 is composed of a pair of upper and lower parts, the piezoelectric electrode 102 is formed on the surface by a thin film forming method such as sputter (RF or DC Sputter). The piezoelectric element 100 is largely divided into a short wave type and a stacked type according to the structure of the ceramic substrate 101. In general, short-wave piezoelectric elements drive voltages of 50 (V / mm) to 1000 (V / mm), and stacked piezoelectric elements stacking a plurality of ceramic substrates 101 operate at lower voltages. Is done.

In one embodiment, the piezoelectric electrode 102 is formed on the surface of the ceramic substrate 101 by a general thin film formation method. The thickness of the piezoelectric electrode 102 is not particularly limited, and may be formed to a thickness of about several μm. Furthermore, it can be implemented by various methods, such as the method of apply | coating a metal paste, and a conductive material is used.

In the piezoelectric element 100 including the ceramic substrate 101 and the piezoelectric electrode 102 described above, polarization is induced in a material in proportion to the pressure when an external pressure F is applied, and mechanical deformation is caused by an external electric field. This takes advantage of the piezoelectric effect in which current is generated.

In addition, the piezoelectric element 100 has a piezoelectric direct effect for converting mechanical energy into electrical energy and a piezoelectric converse effect for converting electrical energy into mechanical energy.

2 is a conceptual diagram illustrating the piezoelectric effect of the piezoelectric element. 2 illustrates the Piezoelectric Direct Effect. As shown, (a) represents the piezoelectric element 100 in the absence of the external pressure (F), at which time the output voltage does not occur. (b) shows the piezoelectric element 100 in the state to which the external pressure F was applied. At this time, the volume of the piezoelectric element 100 decreases, and currents of (+) and (-) are generated in the upper and lower electrodes. (c) shows the piezoelectric element 100 in the state where the stretching force is applied. At this time, the volume of the piezoelectric element 100 is increased compared to the piezoelectric element 100 of (a), and increases compared to the piezoelectric element 100 of (b), and the phenomenon opposite to the piezoelectric element 100 of (b) And (+) and (-) currents are generated at the upper and lower electrodes.

3 is a conceptual diagram illustrating another piezoelectric effect of the piezoelectric element. 3 illustrates a piezoelectric converse effect, and illustrates the basic operation of the piezoelectric element 100 when DC and AC voltages are applied.

As shown, (a ') is a state in which the driving voltage is not applied to the piezoelectric element 100 from the outside, the displacement does not appear at this time. (b ') represents a state in which (+) and (-) driving voltages are applied to upper and lower electrodes of the piezoelectric element 100. When a driving voltage is applied to the piezoelectric element 100, the internal charge of the piezoelectric element 100 and the applied voltage cause repulsion, thereby compressing the piezoelectric element 100. (c ') is a piezoelectric element (opposite to the piezoelectric element 100 of (b') due to the attraction of the internal telephone and the applied voltage when the positive and negative driving voltages are applied to the upper and lower portions of the piezoelectric element 100). 100) increases in volume.

4 is a view illustrating an energy harvesting system according to an embodiment of the present invention. As shown, the energy harvesting system 400 using the piezoelectric element made of an elastic body according to the present invention has a conductive spiral core electrode (Core Electrode) 401, the core electrode (Core Electrode) 401 of the elastic force or elasticity A ferroelectric polymer layer 402 selectively formed on the surface and a surface electrode 403 formed on the surface of the ferroelectric polymer layer 402.

In one embodiment, the center electrode 401 is made of an elastic body including one or more materials of Fe, Ni, Cr, Ti, Mo, Ag, Au, Al, Cu, W or TiN. In addition, since the center electrode 401 has a spiral spring shape, when the external pressure is applied to the center electrode 401, the volume and shape thereof are changed, and when the external pressure is lost, the center electrode 401 has excellent elasticity to return to its original state. Further, the center electrode 401 may be formed of a string, a ball, or a bar. The shape of the center electrode 401 is not limited thereto, and may include various materials including materials having elastic force or elasticity. It can be implemented in shape.

Therefore, it is possible to freely convert external pressure or mechanical vibration in up, down, left, and right directions into electrical energy, and widen the surface area for receiving the external pressure. As a result, the magnitude of the displacement generated by the external pressure increases, and the current and the voltage generated per unit area can be increased.

In one embodiment, the ferroelectric polymer layer is selectively formed on the surface of the center electrode 401 by a dip coating method according to an embodiment of the present invention.

The ferroelectric polymer layer 402 has excellent durability and abrasion resistance due to the strong bonding of fluorine molecules, and has excellent surface corrosion resistance and chemical resistance to chemical inertness and excellent corrosion resistance to chemicals. PVDF and P (VDF) which is a copolymer of PVDF -TrFE), P (VDF-TrFE-CFE) or P (VDF-HFP).

In addition, the material and thickness of the ferroelectric polymer layer 402 are not limited thereto, and may be implemented by various piezoelectric polymers.

In one embodiment, the surface electrode 403 is formed on the surface of the ferroelectric polymer layer 402 selectively formed on the surface of the center electrode 401. The surface electrode 403 is made of a conductive polymer such as polyaniline, polypyrrole or PPs. Or one or more materials of Ti, Cr, Al, Ni, Ag, Pt, Au, La, In, Sn, Pt or Se. The thickness of the surface electrode 403 is not particularly limited, but is formed to a thickness of about several μm, and is not particularly limited.

5 is a view for explaining an energy harvesting system according to another embodiment of the present invention. As shown, the energy harvesting system 200 according to the present invention sequentially selects a ferroelectric polymer layer 402 and a surface electrode 403 selectively on the surface of the center electrode 401 except for some regions. Can be formed repeatedly.

Each of the layers 402 and 403 repeatedly formed has a multi-layer structure on the surface of the center electrode 401 to generate energy and to convert energy between the energy harvesting system 400 by external pressure or mechanical vibration. To improve. This multi-layer structure can be manufactured by a dip coating method according to an embodiment of the present invention.

6 is a flowchart illustrating a method of manufacturing an energy harvesting system according to an embodiment of the present invention. As shown, the energy harvesting system 400 according to the present invention comprises the step of preparing a conductive center electrode (s101), by selectively applying a ferroelectric polymer (Ferroelectric Polymer) layer on the surface of the center electrode by a dip coating method (Dip Coating) Forming (s102), drying and heat treating the center electrode on which the ferroelectric polymer layer is formed (s103), and generating a piezoelectric element by forming a surface electrode on the ferroelectric polymer layer surface (s104). ), S105 aligning the permanent dipole inside the piezoelectric element in a single direction in a high voltage polling process.

In an embodiment, in the preparing of the conductive center electrode (s101), a spiral spring is used as the center electrode 401, and Fe, Ni, Cr, Ti, Mo, Ag, Au, Al, Cu One or more materials of W, Ti or TiN. In addition, the conductive material may be implemented in the form of a string, a ball, or a bar, and thus, the energy harvesting system 400 may be widely used. The center electrode 401 is not limited thereto, and may be implemented in various shapes and sizes including a material having elastic force or elasticity.

In one embodiment, the step (s102) of selectively forming a ferroelectric polymer layer by a dip coating method on the surface of the center electrode P (VDF-TrFE for dip coating) ) Pellet 10wt% -30wt% is dissolved in MEK Solvent to obtain P (VDF-TrFE) polymer solution. The ferroelectric polymer layer 402 is formed by immersing the remaining region except for a portion of the center electrode 401 in the obtained P (VDF-TrFE) polymer solution. In addition, in order to dissolve P (VDF-TrFE) pellets, any one or more than one solution of DMA, DMF, DMSO solution may be used as a solvent.

7 is a view for explaining a dip coating apparatus according to an embodiment of the present invention. As illustrated, dip coating, which is a method of manufacturing an energy harvesting system, is performed by a coating apparatus 700 having a motor 702 on a portion of an upper surface of a shaft having a length in a vertical direction. In addition, dip coating connects the central axis 401 to the P (VDF-TrFE) polymer solution according to the rotation of the motor by connecting the rotation axis of the motor 702 and the center electrode 401 to the connecting member 701. By dipping and dipping. At this time, the driving voltage of the motor 702 is 24V, and the center electrode 401 is immersed in a P (VDF-TrFE) polymer solution at a speed of 0.6 mm / s with a rotational speed of 1 rpm and taken out.

The coating thickness of the P (VDF-TrFE) polymer solution according to the velocity of picking up the center electrode 401 according to the rotational speed of the motor 702 and the rheology of the solution may be described as follows.

는 용액의 코팅 두께

Is the coating thickness of the solution

는 건져올리는 속도

Uplifting speed

는 용액의 점도

Is the viscosity of the solution

는 용액의 밀도

Is the density of the solution

는 표면 장력

Surface tension

The present invention does not limit the piezoelectric polymer contained in the ferroelectric polymer layer 402 to a P (VDF-TrFE) polymer, and is a PVDF copolymer, P (VDF-TrFE-CFE), or P (VDF). All piezoelectric polymers such as -HFP). In addition, the present invention may vary the dipping and extracting speed according to the driving voltage and the rotation speed of the motor 702 according to the thickness of the polymer solution and the ferroelectric polymer layer 402.

In one embodiment, the step (s103) of drying and heat-treating the center electrode on which the ferroelectric polymer layer is formed is performed in a chamber of vacuum or atmospheric pressure. At this time, the temperature inside the chamber for drying is room temperature, the temperature inside the chamber for heat treatment is 100 ℃ ~ 150 ℃. Drying and heat treatment are not limited thereto, and are possible by variously introduced techniques.

In one embodiment, the step (s104) of forming a surface electrode on the surface of the ferroelectric polymer layer to generate a piezoelectric element is a conductive polymer such as polyaniline, polypyrrole or PPs as the surface electrode 403. Form. Formation of the surface electrode 401 made of a conductive polymer may be performed by the s102 step and the dip coating method described with reference to FIG. 7. In addition, after the surface electrode is formed by a dip coating method may further include a drying process.

Further, when the surface electrode 403 is a metal material such as Ti, Cr, Al, Ni, Ag, Pt, Au, La, In, Sn, Pt, or Se, thermal evaporator, electron beam deposition (E-beam) It can be formed by any one of evaporator, RF or DC sputter, E-beam, Electro-plating, and Chemical Vapor Deposition.

Energy harvesting system 400 according to an embodiment of the present invention may be made of a piezoelectric element 500 of a multi-layer (Multi Layer) structure. Manufacturing for the piezoelectric element 500 having a multi-layer structure can be implemented by sequentially repeating the above-described steps s102, s103, and s104.

In one embodiment, the step s105 of unidirectionally arranging the permanent dipole inside the piezoelectric element in the high voltage polling process applies a high voltage to the energy harvesting system 400.

8 is a photograph of an energy harvesting system and a piezoelectric element according to the prior art according to an embodiment of the present invention. As shown (A) is a photograph of the energy harvesting system 400 using a piezoelectric element made of an elastic body according to the present invention, (B) is a photograph of the piezoelectric element 100 of a general film structure according to the prior art.

(A) is 1 mm in thickness, 11 mm in total diameter, and 3 μm in thickness of the coated piezoelectric body, and the total surface area of the coated piezoelectric body is 11 mm x 11 mm x 5 x 0.000543 m 2.

(B) is 22 mm long, 85 mm long, and the thickness of the coated piezoelectric body is 10 µm, and the total surface area of the coated piezoelectric body is 22 mm x 85 mm = 0.00187 m 2. Comparing (A) and (B), the voltage per unit area of (A) is 2.55 V / 0.000543 m 2 = 4.72 KV / m 2, while the voltage per unit area of (B) is 7 V / 0.00187 m 2 = 3.74 KV / m 2. . Accordingly, it can be seen that the energy harvesting system 400 (A) using the piezoelectric element made of an elastic body has a higher voltage at which the unit area is generated than the piezoelectric element 100 (B) of the film structure.

Furthermore, the voltage per unit volume of (A) is (4.72 KV / m 2) / (3 μm) = 1.57 GV / m 3, while the voltage per unit volume of (B) is (3.74 KV / m 2) / (10 μm) = 0.374 GV / m 3. Therefore, it can be seen that the energy harvesting system 400 (A) using the piezoelectric element made of an elastic body has a higher generated voltage per unit volume than the piezoelectric element 100 (B) of the film structure.

Therefore, when the piezoelectric bodies are coated in the same area (A) and (B) in the same area, (A) is expected to have a power generation effect of about 4.2 times higher than that of (B).

The terms used throughout the present specification are terms defined in consideration of functions in the embodiments of the present invention, and may be sufficiently modified according to the intention, custom, etc. of the user or the operator, and thus, the definitions of the terms are used throughout the present specification. It should be made based on the contents.

While the invention has been described with reference to the preferred embodiments, which are referred to by the accompanying drawings, it will be apparent that various modifications are possible without departing from the scope of the invention within the scope covered by the claims set forth below from this description. .

100: piezoelectric element
101: ceramic substrate
102: piezoelectric electrode
400: energy harvesting system
401: center electrode
402: ferroelectric polymer layer
403: surface electrode
500: piezoelectric element of multi-layer structure
700: dip coating device
701: connecting member
702: motor

Claims (19)

A conductive spiral core electrode having an elastic force or elasticity;
A ferroelectric polymer layer selectively formed on the surface of the core electrode;
Surface electrodes formed on the surface of the ferroelectric polymer layer
Energy harvesting system using a piezoelectric element consisting of an elastic body comprising a. The method of claim 1, wherein the center electrode,
Fe, Ni, Cr, Ti, Mo, Ag, Au, Al, Cu, W or TiN energy harvesting system using a piezoelectric element consisting of an elastic body comprising one or more materials. The method of claim 1, wherein the center electrode,
An energy harvesting system using a piezoelectric element made of an elastic body, comprising any one of a spring, a string, a ball, or a bar, and having an elastic force or elasticity. The method of claim 1, wherein the ferroelectric polymer (Ferroelectric Polymer),
Energy harvesting system using a piezoelectric element made of an elastic body, characterized in that the piezoelectric polymer of any one of PVDF, P (VDF-TrFE), P (VDF-TrFE-CFE) or P (VDF-HFP). The method of claim 1, wherein the surface electrode,
Energy harvesting system using a piezoelectric element made of an elastic body, characterized in that it comprises at least one of Ti, Cr, Al, Ni, Ag, Pt, Au, La, In, Sn, Pt or Se. The method of claim 1, wherein the surface electrode,
Energy harvesting system using a piezoelectric element made of an elastic body, characterized in that made of a conductive polymer such as polyaniline, polypyrrole or PPs. A conductive spiral core electrode having an elastic force or elasticity;
A first ferroelectric polymer layer selectively formed on a surface of the core electrode;
A first surface electrode formed on the surface of the first ferroelectric polymer layer;
A second ferroelectric polymer layer formed on the surface of the first surface electrode;
Second surface electrode formed on the surface of the second ferroelectric polymer layer
Energy harvesting system using a piezoelectric element consisting of an elastic body comprising a. According to claim 7, Energy harvesting system using a piezoelectric element made of the elastic body,
An energy harvesting system using a piezoelectric element made of an elastic body, further comprising a third surface electrode and a third ferroelectric polymer layer. According to claim 8, Energy harvesting system using a piezoelectric element made of the elastic body,
An energy harvesting system using a piezoelectric element made of an elastic body, further comprising a plurality of surface electrodes and a plurality of ferroelectric polymer layers on surfaces of the third surface electrode and the third ferroelectric polymer layer. . Preparing a conductive center electrode;
Selectively forming a ferroelectric polymer layer on the surface of the center electrode by a dip coating method;
Drying and heat treating the center electrode on which the ferroelectric polymer layer is formed;
Generating a piezoelectric element by forming a surface electrode on a surface of the ferroelectric polymer layer;
Unidirectionally aligning the permanent dipole inside the piezoelectric element in a high voltage polling process
Energy harvesting system manufacturing method using a piezoelectric element consisting of an elastic body comprising a. The method of claim 10, wherein the step of selectively forming a ferroelectric polymer layer on the surface of the center electrode by a dip coating method,
Piezoelectric element made of an elastomer characterized in that the dip coating of the piezoelectric polymer solution of any one of PVDF, P (VDF-TrFE), P (VDF-TrFE-CFE) or P (VDF-HFP) Energy harvesting system manufacturing method using the. The method of claim 11, wherein the piezoelectric polymer solution,
Pellets of any one of PVDF, P (VDF-TrFE), P (VDF-TrFE-CFE), or P (VDF-HFP), 10wt% ~ 30wt% of MEK, DMA, DMF, DMSO solution Method for producing an energy harvesting system using a piezoelectric element made of an elastic body characterized in that it is mixed with a solution. The method of claim 10, wherein the drying and heat treatment of the center electrode on which the ferroelectric polymer layer is formed is performed.
An energy harvesting system manufacturing method using a piezoelectric element made of an elastic body, characterized in that the drying and heat treatment in a vacuum or atmospheric pressure chamber. The method of claim 13, wherein the drying and heat treatment of the center electrode on which the ferroelectric polymer layer is formed includes:
Method for producing an energy harvesting system using a piezoelectric element made of an elastic body, characterized in that the heat treatment at 100 ℃ ~ 150 ℃ in a vacuum or atmospheric pressure chamber. The method of claim 14, wherein the drying and heat treatment of the center electrode on which the ferroelectric polymer layer is formed comprises:
Energy harvesting system manufacturing method using a piezoelectric element made of an elastic body, characterized in that the drying at room temperature in a vacuum or atmospheric pressure chamber. The method of claim 10, wherein forming a surface electrode on the surface of the ferroelectric polymer layer to generate a piezoelectric element,
If the surface electrode is made of metal, thermal evaporator, e-beam evaporator, sputter (RF or DC sputter), E-beam, electro-plating, chemical vapor deposition ( Chemical Vapor Deposition) method of manufacturing an energy harvesting system using a piezoelectric element made of an elastic body, characterized in that for forming the surface electrode in any one of the manner. The method of claim 10, wherein forming a surface electrode on the surface of the ferroelectric polymer layer to generate a piezoelectric element,
Method for producing an energy harvesting system using a piezoelectric element made of an elastic body, characterized in that the surface electrode can be formed by a dip coating method when the surface electrode is a conductive polymer. 18. The method of claim 17, wherein forming a piezoelectric element by forming a surface electrode on the surface of the ferroelectric polymer layer,
The method of manufacturing an energy harvesting system using a piezoelectric element made of an elastic body, further comprising the step of drying the piezoelectric element on which the surface electrode is formed. The method of claim 10, wherein the piezoelectric element,
A method of manufacturing an energy harvesting system using a piezoelectric element made of an elastic body, characterized in that a plurality of ferroelectric polymer layers and a plurality of surface electrodes are sequentially formed.

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