KR20190107916A - Fabric-based wearable piezoelectric energy harvester and method of manufacturing the same - Google Patents

Abstract

The present invention relates to a fabric-based wearable piezoelectric energy harvester and a manufacturing method thereof. According to one embodiment of the present invention, the fabric-based wearable piezoelectric energy harvester comprises: first and second electrodes positioned to face each other and including conductive fabric; and a polymer layer positioned between the first and second electrodes. The conductive fabric includes a fabric and a conductive material made of metal, conductive polymers, or a combination of the metal and conductive polymers. According to one embodiment of the present invention, the fabric-based wearable piezoelectric energy harvester may be easily deformed by external stimulation (mechanical energy) due to excellent flexibility so that the fabric-based wearable piezoelectric energy harvester may be applied as a wearable energy harvester efficiently using human body movement.

Description

Cloth-based wearable piezoelectric energy harvester and manufacturing method thereof {FABRIC-BASED WEARABLE PIEZOELECTRIC ENERGY HARVESTER AND METHOD OF MANUFACTURING THE SAME}

A cloth-based wearable piezoelectric energy harvester having a heterostructure having a polymer layer interposed between two conductive fabrics and a method of manufacturing the same.

With the recent increase in the use of various wearable devices such as smartphones, tablet PCs, and personal digital assistants (PDAs), technology that can easily supply energy to wearable devices without compromising the portability of these wearable devices Is required.

Wearable devices continue to be exposed to human movement while wearing them. Therefore, various methods for harvesting energy from human movements are emerging as power sources of wearable devices. Among them, research on energy harvester technology based on piezoelectric materials that can directly convert mechanical energy into electrical energy is being actively conducted. Piezoelectric material refers to a material having a positive piezoelectric / reverse piezoelectric effect in which mechanical strain causes a change in polarization in the piezoelectric material or a mechanical strain occurs when a potential difference is applied.

Meanwhile, piezoelectric energy harvesters employed in wearable devices may be in the form of film, fiber, fabric, and the like. In particular, the fabric (fabric) shape is a two-dimensional structure that is utilized in clothing and the like, and thus, human mechanical energy. Because of its efficient use, research is being actively conducted.

However, the conventional two-dimensional piezoelectric energy harvester has a limitation that the thickness of the piezoelectric energy harvester is slightly thicker to be applied to the garment as it has an insulating layer to suppress the short circuit between the stacked two-dimensional layer. In particular, the piezoelectric fabric of the nanoweb (nanoweb) form of the nanofibers (nanofiber) had a limitation that the thickness is not yet secured mechanical strength.

One embodiment relates to a cloth-based wearable piezoelectric energy harvester that is thin and has excellent portability, has both flexibility and mechanical strength and is easy to apply to a wearable device.

Another embodiment relates to a method of manufacturing the cloth-based wearable piezoelectric energy harvester.

According to one embodiment, the first electrode and the second electrode positioned opposite to each other including a conductive fabric, and a polymer layer located between the first electrode and the second electrode, the conductive fabric is a cloth, and a metal, conductive A cloth based wearable piezoelectric energy harvester comprising a conductive material that is a polymer, or a combination thereof.

The polymer layer may be in contact with one surface of the first electrode layer and one surface of the second electrode layer.

The conductive cloth may have a shape in which the conductive material is drawn out between empty spaces present in the cloth.

The polymer layer may have a concave pattern, and the first electrode and the second electrode may each have a convex pattern.

The polymer layer may include a piezoelectric polymer which is polyvinylidene fluoride (PVDF), poly (vinylidene fluoride-trifluoroethylene) [P (VDF-TrFE)], or a combination thereof.

The polymer layer is a flexible polymer, such as silicone rubber, polydimethylsiloxane (PDMS), polyvinyl alcohol (PVA), polyethylene (PE), polyethylene terephthalate (PET), polytetrafluoroethylene (PTFE), polyethylene naphthalate (PEN), polycarbonate (PC), polyarylate ( PAR), ethylene vinyl acetate (EVA), polyimide (PI), polyamide (PA), or a combination thereof.

The polymer layer is a piezoelectric ceramic zinc oxide (ZnO), lead zirconate titanate (PZT), lead titanate (PbTiO ₃ ), lithium niobate (LiNbO ₃ ), potassium niobate (KNbO ₃ ), barium titanate (BaTiO ₃ ), bismuth ferrite (BiFeO ₃ ), carbon nanotubes (nanotube), carbon nanofibers (nanofiber), silver nanowires (nanowire) and silver nanoparticles (nanoparticle) may further include one or two or more selected from.

The fabric is cotton, silk, wool, nylon, polyester, polyvinyl alcohol (PVA), polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), polytetrafluoroethylene (PTFE) It may be one or two or more selected from polycarbonate (PC), polyarylate (PAR), ethylene vinyl acetate (EVA), polyimide (PI) and polyamide (PA).

The conductive polymer is poly (3,4-ethylenedioxythiophene) (PEDOT), poly (p-phenylene sulfide) (PPS), polyaniline (PANI), polypyrrole (PPY) and polyacetylene (PAC), poly (3-hexylthiophene) (P3HT ), poly (p-phenylene vinylene) (PPV), and polythiphene.

The metal is aluminum (Al), copper (Cu), titanium (Ti), gold (Au), silver (Ag), platinum (Pt), nickel (Ni), zinc (Zn), iron (Fe) and cobalt ( Co) may be one or two or more selected from.

The first electrode may include a first passivation layer on an opposite side of the surface facing the polymer layer, and the second electrode may include a second passivation layer on the opposite side of the surface facing the polymer layer. have.

Preparing a polymer layer using the polymer composition,

Preparing a conductive cloth to which a conductive material, which is a metal, a conductive polymer, or a combination thereof, is applied on the cloth,

According to another embodiment of the present invention, the polymer layer is laminated on the conductive fabric and another conductive fabric is laminated on the polymer layer to produce a laminate of heterostructures, wherein the laminate of heterostructures has a temperature of 80 ° C to 120 ° C. And pressing at a pressure of 15 MPa to 30 MPa, heat treating the laminate of the heterostructure at a temperature of 120 ° C. to 160 ° C., and polling the laminate of the heterostructure. Provided is a fabric-based wearable piezoelectric energy harvester manufacturing method.

The polymer layer may be manufactured using a tape casting technique.

The conductive material may be spray coating, dipping method, electroplating, electroless-plating, thermal evaporation, sputtering, physical vapor deposition. It can be applied on the fabric using vapor deposition, chemical vapor deposition or atomic layer deposition.

The method may further include forming protective layers on upper and lower portions of the laminate of the heterostructure before pressing the laminate of the heterostructure.

According to another embodiment, a wearable device including the fabric-based wearable piezoelectric energy harvester described above is provided.

According to one embodiment, a cloth-based wearable piezoelectric energy harvester has a heterostructure including an electrode layer made of a cloth material having excellent flexibility, and a polymer layer made of a polymer material having high flexibility. Accordingly, deformation by external stimulation (mechanical energy) such as pressure or bending is easily performed in the human body such as a finger, elbow, knee, and the like, and thus can be applied as a wearable energy harvester that can effectively use the human body movement.

Another embodiment relates to a method of manufacturing the cloth-based wearable piezoelectric energy harvester, wherein the step of laminating the conductive cloth and the polymer film has a high bonding force between the conductive cloth and the polymer film as the step of stacking the conductive cloth and the polymer film is performed in a rough manner in daily life. It has a high pressure stability and has a high stability as a flexible energy harvester. In addition, the cloth-based wearable piezoelectric energy harvester having a high energy harvest can be manufactured by a simple process.

1 is a cross-sectional view illustrating a cloth-based wearable piezoelectric energy harvester according to an embodiment.
FIG. 2 is a schematic diagram illustrating a heterostructure shape of a cloth-based wearable piezoelectric energy harvester according to an embodiment.
3 is a scanning electron micrograph of the surface of the polymer layer produced by tape casting according to Example 1. FIG.
Figure 4 is a scanning electron micrograph of the cross section of the polymer layer produced by the tape casting according to Example 1.
FIG. 5 is a scanning electron micrograph of the surface of the heterostructure of the conductive fabric / polymer layer / conductive fabric after hot pressing and annealing according to Example 1. FIG.
Figure 6 is a scanning electron micrograph of the cross-section of the heterostructure of the conductive fabric / polymer layer / conductive fabric after high temperature compression and heat treatment according to Example 1.
FIG. 7 is a scanning electron micrograph of the surface of the polymer layer from which the conductive cloth is removed after high temperature compression and heat treatment according to Example 1. FIG.
8 is a scanning electron micrograph of a cross section of a polymer layer from which a conductive cloth is removed after high temperature compression and heat treatment according to Example 1;
FIG. 9 is a scanning electron micrograph of a lamellar structure of the surface of the polymer layer from which the conductive cloth is removed after high temperature compression and heat treatment according to Example 1. FIG.
10 is a graph of thickness before and after heat treatment of the heterostructure of the conductive fabric and the polymer layer after the high temperature compression and the polymer layer produced by the tape casting according to Example 1.
FIG. 11 is a graph of a piezoelectric coefficient d ₃₃ (pC / N) according to a polling voltage of a cloth-based wearable piezoelectric energy harvester having a heterogeneous structure between the conductive cloth and the polymer layer according to Example 1. FIG.
12 and 13 are digital photographs of the cloth-based wearable piezoelectric energy harvester according to the first embodiment.
FIG. 14 is a graph showing an output voltage generated when a finger presses a cloth-based wearable piezoelectric energy harvester polled at 2400 V according to Example 1. FIG.
FIG. 15 is a graph showing an output current generated when a finger presses a cloth-based wearable piezoelectric energy harvester polled at 2400 V according to Example 1. FIG.
FIG. 16 is a graph showing an output voltage generated when the cloth-based wearable piezoelectric energy harvester polled at 2400 V according to Example 1 is bent at an elbow.
FIG. 17 is a graph showing an output current generated when the cloth-based wearable piezoelectric energy harvester polled at 2400 V according to Example 1 is bent at the elbow. FIG.
FIG. 18 is a schematic diagram illustrating a two-step polling process of a cloth-based wearable piezoelectric energy harvester including BaTiO ₃ nanoparticles according to Example 2. FIG.
19 is a schematic view showing a polarization state after the two-step the polling of the cloth-based wearable piezoelectric energy harvester including a BaTiO ₃ nano particles P (VDF-TrFE) and BaTiO ₃ nano particles.

Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art can easily practice. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention.

In the drawings, the thickness of layers, films, panels, regions, etc., are exaggerated for clarity. Like parts are designated by like reference numerals throughout the specification. When a portion of a layer, film, region, plate, etc. is said to be "on top" of another part, this includes not only when the other part is "right over" but also when there is another part in the middle. On the contrary, when a part is "just above" another part, there is no other part in the middle.

A cloth-based wearable piezoelectric energy harvester according to an embodiment will be described with reference to FIG. 1.

1 is a cross-sectional view illustrating a cloth-based wearable piezoelectric energy harvester according to an embodiment.

Referring to FIG. 1, the cloth-based wearable piezoelectric energy harvester 100 includes a first electrode 10, a second electrode 20, and a polymer layer 30.

The first electrode 10 and the second electrode 20 are positioned to face each other, and the polymer layer 30 is positioned between the first electrode 10 and the second electrode 20.

First, the first electrode 10 and the second electrode 20 will be described.

The first electrode 10 and the second electrode 20 include a conductive cloth.

The conductive cloth is a cloth material to which the conductive material is applied, and the conductive material is a metal, a conductive polymer, or a combination thereof.

The conductive fabric is, for example, cotton, silk, wool, nylon, polyester, polyvinyl alcohol (PVA), polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), polytetrafluoroethylene ( High electrical conductivity on fabric surface made of artificial fibers such as PTFE), polycarbonate (PC), polyarylate (PAR), ethylene vinyl acetate (EVA), polyimide (PI) or polyamide (PA) The material may be applied. For example, the conductive material may be aluminum (Al), copper (Cu), titanium (Ti), gold (Au), silver (Ag), platinum (Pt), nickel (Ni), zinc (Zn), iron ( Fe) and cobalt (Co) may be a metal containing one or two or more selected from, for example, the conductive material is poly (3,4-ethylenedioxythiophene) (PEDOT), poly (p-phenylene sulfide 1 or 2 selected from (PPS), polyaniline (PANI), polypyrrole (PPY), polyacetylene (PAC), poly (3-hexylthiophene) (P3HT), poly (p-phenylene vinylene) (PPV) and polythiphene It may be a conductive polymer including the above, but is not limited thereto.

For example, the conductive material may be applied in the form of a thin film on the cloth. As another example, the conductive material may be applied in the form of particles, nanofibers, or the like on the cloth to further secure the flexibility of the device.

The area of the first electrode 10 and the second electrode 20 may be in the range of 10 × 10 mm ² to 50 × 50 mm ² . In this case, the area of the first electrode 10 and the second electrode 20 may be used without limitation as long as the area of the first electrode 10 and the second electrode 20 is smaller than the polymer layer 30 to be described later.

The cloth-based wearable piezoelectric energy harvester 100 according to the exemplary embodiment may improve the portability by adopting a cloth-based material as an electrode material and making the thickness of the electrode thinner.

Next, the polymer layer 30 will be described.

The polymer layer 30 may be positioned between the first electrode 10 and the second electrode 20, and may be in contact with one surface of the first electrode 10 and one surface of the second electrode 20. That is, a separate layer such as an insulating layer may not be interposed between the polymer layer 30 and the first electrode 10 and between the polymer layer 30 and the second electrode 20.

The polymer layer 30 includes a flexible polymer including a piezoelectric polymer or a piezoelectric ceramic material, and the piezoelectric polymer may be, for example, polyvinylidene fluoride (PVDF), poly (vinylidene fluoride-trifluoroethylene) [P (VDF-TrFE)]. , Or combinations thereof, and flexible polymers include silicone rubber, polydimethylsiloxane (PDMS), polyvinyl alcohol (PVA), polyethylene (PE), polyethylene terephthalate (PET), polytetrafluoroethylene (PTFE), polyethylene naphthalate (PEN), polycarbonate ( PC), polyarylate (PAR), ethylene vinyl acetate (EVA), polyimide (PI), polyamide (PA), or a combination thereof, but is not limited thereto, and may be a polymer having piezoelectric properties or flexibility. Can be used without restrictions.

The polymer layer 30 may be formed by further including a piezoelectric ceramic in the above-described polymer. If the polymer layer includes the above-described flexible polymer, it should further include a ceramic material having piezoelectric properties.

The piezoelectric ceramics include, for example, zinc oxide (ZnO), lead zirconate titanate (PZT), lead titanate (PbTiO ₃ ), lithium niobate (LiNbO ₃ ), potassium niobate (KNbO ₃ ), barium titanate (BaTiO ₃ ), and bismuth ferrite (BiFeO) ₃ ) may be one or two or more selected from, but is not limited thereto. The piezoelectric ceramic content may be appropriately selected in consideration of electrical characteristics and flexibility of the cloth-based wearable piezoelectric energy harvester 100.

PVDF or P (VDF-TrFE) having piezoelectric properties in the polymer layer 30 may further include a nanostructured material. The material having the nanostructure may be, for example, one or two or more selected from carbon nanotubes, carbon nanofibers, silver nanowires, and silver nanoparticles, but is not limited thereto. It is not. The content of the nanomaterial may be appropriately selected in consideration of electrical characteristics and flexibility of the cloth-based wearable piezoelectric energy harvester 100.

The cloth-based wearable piezoelectric energy harvester 100 according to an exemplary embodiment may secure an advantageous flexibility to be applied to a wearable device by employing a polymer material in a piezoelectric layer having piezoelectric properties.

The thickness of the polymer layer 30 may be such that the thickness of the first electrode 10 and the second electrode 20 does not come into contact with each other after the high temperature compression according to the fabric geometry. It can be used without restrictions. For example, the thickness of the polymer layer 30 may be in the range of about 70 μm to 150 μm, but is not limited thereto.

For example, the polymer layer 30 may have a concave pattern, and the first electrode 10 and the second electrode 20 may each have a convex pattern. This will be described with reference to FIG. 2.

FIG. 2 is a schematic diagram illustrating a heterostructure shape of a cloth-based wearable piezoelectric energy harvester according to an embodiment.

Referring to FIG. 2, the polymer layer 30 has a concave pattern, and the first electrode 10 and the second electrode 20 have convex patterns, respectively, and the first electrode / polymer layer / second electrode laminate is As a result of high temperature compression and heat treatment, the heterostructure has a shape.

For example, the area of the polymer layer 30 may be in the range of 20 × 20 mm ² to 60 × 60 mm ² and concave morphology along the surface of the convex morphology of the conductive fabric after hot pressing. ) And its thickness may be in the range of 20 μm to 120 μm. At this time, the thickness of the polymer layer 30 may vary depending on the geometry of the fabric used.

Referring back to FIG. 1, the cloth-based wearable piezoelectric energy harvester 100 includes a first protective layer 40 on an opposite side of the surface where the first electrode 10 faces the polymer layer 30. The second electrode 20 includes a second protective layer 50 on a surface opposite to the surface facing the polymer layer 30.

The material of the protective layers 40 and 50 may be used without limitation as long as the material does not melt at a high temperature compression temperature and does not have a mechanical or chemical effect on the first and second electrodes 10 and 20 and the polymer layer 30. It is possible. In this case, the protective layers 40 and 50 may be used without limitation as long as they have an area larger than the areas of the first and second electrodes 10 and 20 and the area of the polymer layer 30.

According to another embodiment, a wearable device including the fabric-based wearable piezoelectric energy harvester described above is provided. The wearable device may be implemented as various products such as a smart watch, a smart band, and a smart glass.

According to another embodiment, a method of manufacturing a cloth-based wearable piezoelectric energy harvester is provided.

The method of manufacturing the cloth-based wearable piezoelectric energy harvester may include preparing a polymer layer using a polymer composition (S1), and manufacturing a conductive cloth by applying a conductive material, such as a metal, a conductive polymer, or a combination thereof, onto the cloth (S2). ), Stacking the polymer layer on the conductive fabric and stacking another conductive fabric on the polymer layer (S3) to produce a laminate of the heterostructure, the surface of the polymer layer in contact with the conductive fabric laminate In the temperature range of 80 ° C to 120 ° C that can only be melted, the step of pressing at a suitable temperature according to the polymer material and a pressure of 15 MPa to 30 MPa (S4), a phase having piezoelectric properties of the polymer layer In order to increase the crystallinity of the (), the heterostructure laminate is applied to the piezoelectric material of the polymer layer in the temperature range of 80 ℃ to 160 ℃. Another step of heat treatment at an appropriate temperature (S5), and a step (S6) for polling (poling), a layered product of the heterostructure.

First, the step (S1) of manufacturing the polymer layer will be described.

The polymer layer may be manufactured by, for example, tape casting. In proceeding with the tape casting, the concentration of the solution in which the polymer is dissolved may be used, for example, in the range of about 20 wt% to 30 wt%. For example, the polymer layer may be generated by dropping the solution in which the polymer is dissolved and then tape casting at a speed of 1 cm / sec to 3 cm / sec. The thickness of the polymer layer may for example be in the range of about 70 μm to 150 μm. For example, a doctor blade used for tape casting has a height of 500 μm to 1000 μm and can be adjusted at a speed of 1 cm / sec to 3 cm / sec, but is not limited thereto.

In this case, the thickness of the polymer layer may be used without limitation as long as the two conductive fabrics do not come into contact with each other after high temperature compression according to the geometry of the fabric. The solvent used for the tape casting may be used without limitation as long as it can dissolve materials of functional polymer films such as tetrahydrofuran (THF), methyl ethyl ketone (MEK), dimethylformamide (DMF), and dimethyl sulfoxide (DMSO). .

The content of the piezoelectric polymer is as described above.

Next, the step (S2) of preparing a conductive cloth will be described.

The conductive fabric is manufactured by applying a conductive material which is a metal, a conductive polymer, or a combination thereof on the fabric material. The content of the cloth, the metal and the conductive polymer is as described above.

The conductive cloth may be spray coated, dipping method, electroplating, electroless-plating, thermal evaporation of a solution or ink containing a metal or polymer precursor, It may be prepared by coating the fabric using a method such as sputtering, physical vapor deposition, chemical vapor deposition, or atomic layer deposition. The conductive layer manufactured based on the fabric structure among the deposition methods listed above is not limited to a specific deposition method.

Subsequently, the polymer layer is laminated on the conductive fabric and another conductive fabric is laminated on the polymer layer to prepare a laminate having a heterogeneous structure (S3). Other layers, such as an insulating layer, may not be interposed between the conductive cloth and the polymer layer.

Subsequently, the laminate of the heterostructure is pressed at a suitable temperature according to the polymer material and a pressure of 15 MPa to 30 MPa in the temperature range of 80 ℃ to 120 ℃ that can only melt the surface of the polymer layer in contact with the conductive wire cloth ( It goes through S4). The heterostructure of the conductive cloth and the polymer layer of the present invention is manufactured using such high temperature compression. For example, before pressing the laminate of the heterostructure, the method may further include forming protective layers on the upper and lower portions of the laminate of the heterostructure, respectively. The protective layer may be used without limitation as long as it does not melt at a high temperature compression temperature and does not have a mechanical or chemical effect on the conductive cloth and the polymer layer. In more detail, the pressing may be performed at a temperature of 100 ° C. or more and 120 ° C. or less and a pressure of 15 MPa to 30 MPa, but is not limited thereto.

Between the two metal plates of the hot presser, the hot pressing is carried out with the protective film from the bottom, the lower conductive cloth, the polymer layer, the upper conductive cloth, and the protective layer stacked in the center of the metal plate. Can proceed. In order to increase the interfacial strength in the hot pressing process, a pressure condition of 15 MPa to 30M Pa and a temperature range of 80 ° C. to 120 ° C., which melt only the surface of the polymer in contact with the conductive layer cloth, for example, P (VDF -TrFE) to fabricate a cloth-based wearable piezoelectric energy harvester having the heterostructure by applying the P (VDF-TrFE) film at a temperature of 100 ℃ to 110 ℃ that does not melt, but only the surface in contact with the conductive cloth under the pressure conditions. can do. In addition, it is characterized in that the compression in the temperature range that can be combined with the conductive cloth without melting the polymer layer.

Subsequently, the laminate of the heterostructure is subjected to heat treatment at an appropriate temperature according to the piezoelectric material of the polymer layer in a temperature range of 80 ° C. to 160 ° C. (S5).

By heat treatment at the temperature it is possible to increase the crystallinity of the phase showing the piezoelectric properties of the polymer layer. For example, the crystallinity may increase the crystallinity of the β phase, which is a ferroelectric phase of P (VDF-TrFE). The heat treatment is carried out at an appropriate temperature, for example P (VDF-TrFE), depending on the piezoelectric material of the polymer layer in the temperature range of 80 ° C. to 160 ° C., for example at a vacuum or atmospheric pressure of 0.1 MPa or less for optimum crystallinity of the piezo phase. In the case of 1 to 3 hours may be carried out at a temperature of 120 ℃ to 140 ℃. At this time, the polymer is characterized in that the heat treatment in the temperature range does not melt. After the heat treatment, the laminate of the heterostructure is immediately taken out of the vacuum oven to room temperature, and cooled by quenching at room temperature and atmospheric pressure.

Subsequently, in order to further secure the piezoelectric properties, the step S6 is performed to poll the laminate of the heterostructure.

Polling temperature is slightly lower than Curie temperature (T _c ) to reduce the coercive field, for example P (VDF-TrFE), Curie temperature is 120 ℃ and Polling temperature is 100 ℃. Have The polling process increases the temperature from room temperature to near Curie temperature while applying an electric field above the anti-electric field, and then maintains the temperature for 1 hour to 2 hours and then lowers the temperature to room temperature to remove the electric field. At this time, in order to prevent a short during the polling process, the electric field may be raised at a predetermined interval without raising the electric field at one time or more, and then heated.

According to the fabric-based wearable piezoelectric energy harvester manufacturing method according to the embodiment, the step of laminating the conductive fabric and the polymer layer is carried out at a high temperature, high pressure to have a high bonding force between the conductive fabric and the polymer layer and to withstand the harsh pressure in everyday life It can have a high stability as a flexible energy harvester. In addition, by using tape casting and high temperature compression, low cost, large size, and mass production are possible.

Through the following examples will be described in more detail the embodiment of the present invention. However, the following examples are merely for illustrative purposes and do not limit the scope of the present invention.

Fabrication of Cloth-based Wearable Piezoelectric Energy Harvesters

Example 1

(1) Polymer layer production

To make the polymer layer, poly (vinylidene fluoride-trifluoroethylene) [P (VDF-TrFE)] pellets with 75% mol% were added to methyl ethyl ketone (MEK) solvent at 30 wt% and the solution was dissolved for 24 hours. Sonication processing. The P (VDF-TrFE) pellet is then completely dissolved in MEK solvent by sterling for 24 hours. 30 ml of the finished P (VDF-TrFE) solution is dropped onto a 20 × 30 cm ² glass, then tape casting a doctor blade set to a height of 650 μm at a speed of 1 cm / sec. ) do. When the MEK solvent evaporates, it is dried for 1 hour at 100 ° C. in a vacuum oven to completely evaporate and remove the MEK solvent, cool, and cut the film into 3 × 3 cm ² areas.

(2) conductive cloth preparation

Use commercially available nickel and copper coated polyester cloth (Less EMF Inc.) as the conductive cloth.

(3) fabrication of heterostructure laminate and hot pressing process step

Polyimide film, protective layer from below, between 2 metal plates of hot presser (Carver Press) for the heterostructure of conductive fabric and polymer layer, 2 × 2 cm ² Area conductive cloth, 3 × 3 cm ² Area P (VDF-TrFE) film, polyimide film, 2 × 2 cm ² After raising the area of conductive cloth and polyimide film, the center of each film and cloth is centered on the metal plate and pressed for 2 minutes or more at 110 ° C. at a pressure of 15 MPa. In this case, the conductive cloth is set to have an area smaller than that of the P (VDF-TrFE) film. The protective layer is set to have an area in a range larger than that of the P (VDF-TrFE) film.

(4) annealing step

In order to increase the crystallinity of the ferroelectric β-phase of the heterostructured P (VDF-TrFE) film, heat treatment was performed at 130 ° C. for 2 hours in a vacuum of 0.1 MPa or less in a vacuum oven. After the heat treatment, it is immediately transferred to room temperature and quenched, thereby suppressing the size of the β phase lamellar, which is a ferroelectric phase, so that the lamellars are easily aligned with the P (VDF-TrFE) surface.

(5) polling step

In order to align spontaneous polarization in the ferroelectric β phase of the P (VDF-TrFE) film in a direction perpendicular to the film surface, a voltage of 300 V to 2400 V is applied to the conductive cloth to poll. While maintaining the voltage applied to raise the temperature from room temperature to 100 ℃ and then maintained for 1 hour and lowered again to room temperature and stop the voltage application.

Evaluation 1: Scanning Electron Microscopy

3 is a scanning electron micrograph of the surface of the polymer layer produced by the tape casting according to Example 1, Figure 4 is a scanning electron microscope picture of the cross section of the polymer layer produced by the tape casting according to Example 1.

3 and 4, the surface of the P (VDF-TrFE) film is composed of particles having a diameter of 50 nm or less. It can be seen that the cross section of the P (VDF-TrFE) film has a uniform thickness.

5 is a scanning electron micrograph of the surface of the heterostructure of the conductive fabric / polymer layer / conductive fabric after high temperature compression and heat treatment according to Example 1, Figure 6 is a conductive cloth / after high temperature compression and heat treatment according to Example 1 Scanning electron micrographs of cross sections of heterostructures of polymer layers / conductive fabrics.

Referring to FIGS. 5 and 6, the P (VDF-TrFE) film is drawn out from the space between the yarn and the yarn of the conductive fabric after high temperature compression. It can be seen that the cross-section of the heterostructure has a shape in which a concave P (VDF-TrFE) film is bonded along the shape of the convex conductive cloth.

FIG. 7 is a scanning electron micrograph of the surface of the polymer layer from which the conductive cloth is removed after hot pressing and heat treatment according to Example 1, and FIG. 8 is a cross section of the polymer layer from which the conductive cloth is removed after hot pressing and heat treatment according to Example 1 Scanning electron micrograph.

Referring to FIGS. 7 and 8, it can be seen that the P (VDF-TrFE) surface has a concave shape opposite to the convex shape of the conductive cloth.

FIG. 9 is a scanning electron micrograph of a lamellar on the surface of the polymer layer from which the conductive cloth is removed after high temperature compression and heat treatment according to Example 1. FIG.

Referring to FIG. 9, the P (VDF-TrFE) surface has a lamellar structure rather than particles as shown in FIG. 3 by heat treatment. At this time, the lamellar has a small form of growth is inhibited by? Ching and has a diameter of 10 nm to 50 nm and a length of 100 nm to 500 nm. Shorter lamellae may be more easily aligned with the surface of the functional polymer film, thereby lowering the coercive field. In addition, the lamellas are aligned in a constant direction by hot pressing, so that a dipole moment perpendicular to the chains constituting the lamellas is aligned perpendicular to the surface. As the small lamellars are aligned in a constant direction, the antistatic field affecting the polling field for polarization is expected to be lowered and the piezoelectric potential is increased.

Evaluation 2: Observation of Thickness of Heterostructure Before and After Hot Pressing

10 is a graph of thickness before and after heat treatment of the heterostructure of the conductive fabric and the polymer layer after the high temperature compression and the polymer layer produced by the tape casting according to Example 1.

Referring to FIG. 10, it can be seen that the thickness of the conductive cloth is 80 μm and the variation in thickness and thickness is uniform as the process proceeds.

Evaluation 3: Piezoelectric Factor d According to Polling Voltage ₃₃  graph of (pC / N)

FIG. 11 is a graph of a piezoelectric coefficient d ₃₃ (pC / N) according to a polling voltage of a cloth-based wearable piezoelectric energy harvester having a heterogeneous structure between the conductive cloth and the polymer layer according to Example 1. FIG.

Referring to FIG. 11, the absolute value of d ₃₃ increases linearly with the polling voltage and has a maximum value of −32 pC / N at a polling voltage of 2400 V. FIG.

Evaluation 4: appearance and bending evaluation

12 and 13 are digital photographs of the cloth-based wearable piezoelectric energy harvester according to the first embodiment.

Referring to FIG. 12, the area of the P (VDF-TrFE) film is 3 × 3 cm ² and the area of the conductive cloth is 2 × 2 cm ² . Referring to FIG. 13, it can be seen that the wearable device operates normally even after bending up to 170 °, and has high flexibility and stability. This is due to a property that can simultaneously serve as a substrate (substrate) of the polyester transition metal and supporting the P (VDF-TrFE) film.

Evaluation 5: Piezoelectric Property Evaluation

FIG. 14 is a graph showing an output voltage generated when a finger presses a cloth-based wearable piezoelectric energy harvester polled at 2400 V according to Example 1, and FIG. 15 is a cloth-based wearable piezoelectric polled at 2400 V according to Example 1. FIG. This graph shows the output current generated when the energy harvester is pressed with a finger. Referring to FIGS. 14 and 15, it can be seen that when a finger is pressed, a voltage of about 4 V and a current of 50 nA are generated. This is because the height and thickness of the peak at the time of pressing and releasing are different because of the strain rate.

FIG. 16 is a graph showing an output voltage generated when the cloth-based wearable piezoelectric energy harvester polled at 2400 V according to Example 1 is bent at an elbow, and FIG. 17 is a cloth-based wearable piezoelectric polled at 2400 V according to Example 1. FIG. This graph shows the output current generated when the energy harvester is bent at the elbow.

Referring to FIGS. 16 and 17, a voltage of about 4.5 V and a current of 45 nA were generated when bending at the elbow. The difference between the height and thickness of the peak during bending and unfolding is due to the different strains.

(Reference Example)

Example 2

It relates to a method of manufacturing a conductive cloth that can be used in place of nickel and copper coated polyester cloth of Example 1 using a dipping method. A method of manufacturing a conductive silk cloth by coating a CNT on a surface by immersing a fabric made of silk, which is a natural fiber instead of an artificial fiber polyester, in a solution containing conductive carbon nanotubes (CNT). to be.

According to this embodiment, tip sonication is performed for 20 minutes in an aqueous solution in which conductive multi-walled carbon nanotube (MWCNT) and surfactant sodium dodecylbenzenesulfonate (SDBS) are added at concentrations of 10 mg / ml and 20 mg / ml, respectively. Treatment with tip sonication and sonication for 60 minutes yields a well dispersed solution of MWCNTs. After immersing the silk cloth in MWCNT solution for 5-7 seconds, it is dried for 15 minutes at 100 ° C. in a vacuum oven and cooled at room temperature. Repeating the process of immersing in the MWCNT solution, drying and cooling 3 to 5 times, a conductive cloth that can be applied to the cloth-based wearable piezoelectric energy harvester is manufactured.

Example  3

In the method for producing a piezoelectric ceramic-piezoelectric polymer composite (composite) consisting of piezoelectric barium titanate (BaTiO ₃ ) nanoparticles and P (VDF-TrFE) film can be used in place of the P (VDF-TrFE) film of Example 1 It is about. The piezoelectric ceramic BaTiO ₃ has a positive d ₃₃ value and the piezoelectric polymer P (VDF-TrFE) has a negative d ₃₃ value and has a different polling process from the representative embodiment.

To fabricate a cloth-based wearable piezoelectric energy harvester containing BaTiO ₃ nanoparticles, P (VDF-TrFE) pellets and 200-700 nm-sized BaTiO ₃ nanoparticles were placed in MEK solvent and subjected to P (VDF) through sonication and sterling. Dissolve the pellet and disperse the BaTiO ₃ nanoparticles. Thereafter, tape casting, drying, high temperature compression, and heat treatment are performed in the same process as the representative embodiment of the present invention.

FIG. 18 is a schematic diagram illustrating a two-step polling process of a cloth-based wearable piezoelectric energy harvester including BaTiO ₃ nanoparticles according to Example 2. FIG. Referring to FIG. 18, BaTiO ₃ nanoparticles have a coercive field of 7 MV / m and P (VDF-TrFE) has a constant field of 40 MV / m to 50 MV / m at 100 ° C. FIG. The first polling is performed in the same manner as the representative embodiment to align the polarization of P (VDF-TrFE). The second polling connects the electrodes in reverse, polling them with an electric field of about 10 MV / m lower than 40 MV / m to align the polarization of BaTiO ₃ nanoparticles in the opposite direction.

19 is a schematic view showing a polarization state after the two-step the polling of the cloth-based wearable piezoelectric energy harvester including a BaTiO ₃ nano particles P (VDF-TrFE) and BaTiO ₃ nano particles. Referring to FIG. 19, P (VDF-TrFE) and BaTiO ₃ nanoparticles have polarization in opposite directions, but BaTiO ₃ has a positive d ₃₃ value and P (VDF-TrFE) has a negative d ₃₃ value mixture. Under this mechanical stress, P (VDF-TrFE) produces a potential difference in the same direction as the polarization direction, while BaTiO ₃ nanoparticles produce a potential difference in the opposite direction to the polarization direction, resulting in two materials in the same direction. Produces a potential difference of. Thus, the mixture may have improved piezoelectric properties than the P (VDF-TrFE) film.

Although the preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concepts of the present invention defined in the following claims are also provided. It belongs to the scope of the invention.

100 Cloth Based Wearable Piezo Energy Harvester
10 first electrode
20 Second electrode 30 Polymer layer
40 First passivation layer 50 Second passivation layer

Claims (16)

A first electrode and a second electrode positioned opposite each other and comprising a conductive cloth, and
It includes a polymer layer positioned between the first electrode and the second electrode,
The conductive cloth includes a cloth and a conductive material which is a metal, a conductive polymer, or a combination thereof.
Cloth based wearable piezo energy harvester. In claim 1,
The polymer layer is a cloth-based wearable piezoelectric energy harvester is positioned in contact with one surface of the first electrode layer and one surface of the second electrode layer. In claim 1,
The conductive cloth is a cloth-based wearable piezoelectric energy harvester having a shape in which the conductive material escapes between the empty spaces present in the cloth. In claim 1,
The polymer layer has a concave pattern, the first electrode and the second electrode is a cloth-based wearable piezoelectric energy harvester having a convex pattern, respectively. In claim 1,
The polymer layer is a cloth-based wearable piezoelectric energy harvester comprising a piezoelectric polymer which is polyvinylidene fluoride (PVDF), poly (vinylidene fluoride-trifluoroethylene) [P (VDF-TrFE)], or a combination thereof. In claim 1,
The polymer layer is silicone rubber, polydimethylsiloxane (PDMS), polyvinyl alcohol (PVA), polyethylene (PE), polyethylene terephthalate (PET), polytetrafluoroethylene (PTFE), polyethylene naphthalate (PEN), polycarbonate (PC), polyarylate (PAR), A cloth-based wearable piezoelectric energy harvester comprising a flexible polymer that is ethylene vinyl acetate (EVA), polyimide (PI), polyamide (PA), or a combination thereof. In claim 1,
The polymer layer is zinc oxide (ZnO), lead zirconate titanate (PZT), lead titanate (PbTiO ₃ ), lithium niobate (LiNbO ₃ ), potassium niobate (KNbO ₃ ), barium titanate (BaTiO ₃ ), bismuth ferrite (BiFeO ₃₎ ), a cloth-based wearable piezoelectric energy harvester further comprising one or two or more selected from carbon nanotubes, carbon nanofibers, silver nanowires, and silver nanoparticles. In claim 1,
The fabric is cotton, silk, wool, nylon, polyester, polyvinyl alcohol (PVA), polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), polytetrafluoroethylene (PTFE) Fabric-based wearable piezoelectric energy harvesters, one or more selected from polycarbonate (PC), polyarylate (PAR), ethylene vinyl acetate (EVA), polyimide (PI), and polyamide (PA). In claim 1,
The conductive polymer is poly (3,4-ethylenedioxythiophene) (PEDOT), poly (p-phenylene sulfide) (PPS), polyaniline (PANI), polypyrrole (PPY), polyacetylene (PAC), poly (3-hexylthiophene) (P3HT ), one or more fabric-based wearable piezoelectric energy harvesters selected from poly (p-phenylene vinylene) (PPV) and polythiphene. In claim 1,
The metal is aluminum (Al), copper (Cu), titanium (Ti), gold (Au), silver (Ag), platinum (Pt), nickel (Ni), zinc (Zn), iron (Fe) and cobalt ( A cloth-based wearable piezoelectric energy harvester, which is one or two or more selected from Co). In claim 1,
The first electrode includes a first protective layer on a surface opposite to a surface facing the polymer layer,
The second electrode includes a second protective layer on the opposite side of the surface facing the polymer layer
Cloth based wearable piezo energy harvester. Preparing a polymer layer using the polymer composition,
Preparing a conductive cloth to which a conductive material, which is a metal, a conductive polymer, or a combination thereof, is applied on the cloth,
Stacking the polymer layer on the conductive fabric and stacking another conductive fabric on the polymer layer to manufacture a laminate having a heterogeneous structure;
Pressing the laminate of the heterostructures at a temperature of 80 ° C. or more and 120 ° C. or less and a pressure of 15 MPa to 30 MPa,
Heat-treating the laminate of the heterostructure at a temperature of 80 ° C. to 160 ° C., and
Polling the laminate of the heterostructures
Cloth-based wearable piezoelectric energy harvester manufacturing method comprising a. In claim 12,
The polymer layer is a cloth-based wearable piezoelectric energy harvester manufacturing method produced using a tape casting (tape casting) technique. In claim 12,
The conductive material may be spray coating, dipping method, electroplating, electroless-plating, thermal evaporation, sputtering, physical vapor deposition. A fabric-based wearable piezoelectric energy harvester manufacturing method applied to the fabric using vapor deposition, chemical vapor deposition, or atomic layer deposition. In claim 12,
And forming protective layers on the upper and lower portions of the laminate of the heterostructure, respectively, before pressing the laminate of the heterostructure. A wearable device comprising a cloth-based wearable piezoelectric energy harvester according to any one of claims 1 to 11.

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