JP2018010981A - Thermoelectric conversion module and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a space-saving thermoelectric conversion module of large thermoelectric output, using a P type conductive polymer material.SOLUTION: In a thermoelectric conversion module 100, a conductive polymer layer 1 having P type thermoelectric characteristics and a metal layer 2 are laminated alternately without gap between two metal layers 2 located at the opposite ends, and an isolation layer 3 and electrode layers 4, 5 are boded to the opposite sides of the conductive polymer layer 1. The electrode layers 4, 5 are located at the first end on the front of the conductive polymer layer 1, and the second end on the opposite side to the first end of the back, and the conductive polymer layer 1 and metal layer 2 are connected electrically via the electrode layers 4, 5.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a thermoelectric conversion module, and more specifically, to a thermoelectric conversion module using a conductive polymer as a thermoelectric material and a manufacturing method thereof.

  Thermoelectric conversion is a technique for converting heat energy and electrical energy to each other using a solid thermoelectric conversion module. Of these, the technology for converting thermal energy into electrical energy is called thermoelectric power generation and is based on the Seebeck effect, which is one of the thermoelectric effects. In thermoelectric power generation, the temperature difference between both ends of the thermoelectric conversion module is directly converted into electrical energy.

  Conductive polymers have advantages such as light weight, flexibility, and non-toxicity as a material, and the manufacturing process has advantages such as mass production, large area production, and low cost, and is expected to be applied to electrical and electronic components. Material. For example, Patent Document 1 discloses a so-called pi (π) type thermoelectric conversion module in which electrodes are arranged above and below a structure in which conductive films containing a conductive polymer and insulating heat insulators are alternately adjacent to each other. Yes.

  In the π-type thermoelectric conversion module of Patent Document 1, conductive wires that electrically connect the upper and lower electrodes are provided in an insulating heat insulator between conductive films made of a P-type thermoelectric material (conductive polymer). Therefore, an extra space is required for the arrangement of the conductive wires and the upper and lower electrodes.

International Publication WO2013 / 065856

  It is an object of the present invention to provide a space-saving thermoelectric conversion module that uses a P-type conductive polymer material and has a large thermoelectric output.

  In one embodiment of the present invention, a conductive polymer layer having a P-type thermoelectric property and a metal layer are alternately stacked between two metal layers located at both ends without any gap, and insulation is provided on both surfaces of the conductive polymer layer. The electrode layer is located at the first end of the surface of the conductive polymer layer and the second end opposite to the first end of the back surface, and is electrically conductive. Provided is a thermoelectric conversion module in which a polymer layer and a metal layer are electrically connected via an electrode layer.

  In another aspect of the present invention, the conventional upper and lower electrodes are unnecessary, and a current during power generation is generated between the P-type conductive polymer layer and the metal layer that are stacked without any gap through the interlayer electrode layer. Since it flows, a space-saving thermoelectric conversion module having a large thermoelectric output per unit area can be obtained.

  In one embodiment of the present invention, a method for manufacturing a thermoelectric conversion module is provided. The manufacturing method includes the steps of (a) preparing a first metal layer in which an electrode layer is formed at an end of a surface and an insulating layer is formed in a region other than the electrode layer on the surface; Preparing a second metal layer in which an electrode layer is formed on the surface and an insulating layer is formed in a region other than the electrode layers on both surfaces, and the end portions on both surfaces are positioned on opposite sides of the front surface and the back surface And (c) preparing at least two or more conductive polymer layers and forming a laminated structure in which a second metal layer is bonded between two adjacent conductive polymer layers, and (d) Bonding a first metal layer to the surface of each of the conductive polymer layers at both ends of the laminated structure so that the electrode layer and the insulating layer on the surface are in contact with each other.

  In another aspect of the present invention, each layer constituting the thermoelectric conversion module is prepared in advance, and according to the required thermoelectric output, a required number of layers are laminated (bonded) without gaps in a relatively simple method. A space-saving thermoelectric conversion module having a large thermoelectric output per unit area can be obtained.

It is sectional drawing which shows the structure of the thermoelectric conversion module of one Embodiment of this invention. It is a figure which shows the manufacturing process of the thermoelectric conversion module of one Embodiment of this invention. It is a figure for demonstrating the manufacturing process of the thermoelectric conversion module of one Embodiment of this invention. It is a figure which shows the external appearance of the thermoelectric conversion module of one Example of this invention. It is a figure which shows the characteristic of the thermoelectric conversion module of one Example of this invention. It is a figure which shows the characteristic of the thermoelectric conversion module of one Example of this invention. It is a figure which shows the characteristic of the thermoelectric conversion module of one Example of this invention. It is a figure which shows the contact resistance of the electrode (metal) material which can be utilized with the thermoelectric conversion module of one Example of this invention.

  Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view showing a configuration of a thermoelectric conversion module 100 according to an embodiment of the present invention. As shown to (a), the thermoelectric conversion module 100 is equipped with the structure where the conductive polymer layer 1 and the metal layer 2 were laminated | stacked alternately. In that case, the metal layer 2 is arrange | positioned at both ends. The conductive polymer layer 1 is made of a material having P-type thermoelectric characteristics. The metal layer 2 is made of a metal for electrical connection. Therefore, the thermoelectric conversion module according to one embodiment of the present invention has a configuration in which P-type thermoelectric materials (conductive polymer layers) and electrical connection materials (metal layers) are alternately stacked.

  The conductive polymer layer 1 is made of, for example, a PEDOT: PSS film. PEDOT: PSS is a charge transfer complex composed of poly (3,4-ethylenedioxythiophene) (PEDOT) and poly (styrenesulfonate) (PSS). PEDOT: PSS has P-type thermoelectric properties. In PEDOT: PSS, carriers are supplied to PEDOT from PSS acting as a dopant, and this results in good conductivity in PEDOT. Further, by adding ethylene glycol (EG) during the formation of the PEDOT: PSS film, the electric conductivity of the PEDOT: PSS film after film formation with the same crystal orientation can be improved.

  The metal layer 2 is made of, for example, a nickel (Ni) film. Since a general metal is N-type in terms of thermoelectric characteristics, the metal layer 2 is preferably a metal that has not only electrical connection but also high N-type thermoelectric characteristics in terms of module configuration. Ni has N-type thermoelectric properties and has a Seebeck coefficient of 20 mV / K. However, as will be described in detail later, since the contact resistance between the Ni film and the PEDOT: PSS film is large, the electrode layer described below is used in the present invention.

  FIG. 1B shows details of the configuration including the metal layer 2 between the two conductive polymer layers 1, that is, the region surrounded by the ellipse of FIG. The insulating layer 3 and the electrode layers 4 and 5 are bonded to both surfaces of the metal layer 2. The electrode layer 4 is located at one end of the surface of the metal layer 2, and the electrode layer 5 is located at the other end opposite to the one end of the back surface.

  In FIG. 1 (b), there is a space between the insulating layer 3 and the electrode layers 4, 5 and the conductive polymer layer 1, but this is a space for easy understanding of the configuration. The insulating layer 3 and the electrode layers 4 and 5 are also bonded to the conductive polymer layer 1. Accordingly, when viewed from the inner surface of the two conductive polymer layers 1 of (b), the electrode layer 4 is located at one end of the surface of one of the conductive polymer layers 1, and the electrode layer 5 is the other The conductive polymer layer 1 is located at the other end opposite to one end of the surface. As a result, the conductive polymer layer 1 and the metal layer 2 are electrically connected in series via the electrode layers 4 and 5.

  FIG.1 (c) is an image figure which shows a mode that the thermoelectric conversion module 100 of the state (multistage) in which the structure (laminated structure) of (b) was joined is produced | generated by thermoelectric conversion. There is a heat source on the lower side of the thermoelectric conversion module and it is heated, and the current generated in the module by the Seebeck effect flows sequentially as shown by the arrow 6 and is output to the external circuit and radiates heat from the upper side. In the module, a current generated in the conductive polymer layer 1 and flowing upward flows into the adjacent metal layer 1 through the electrode layer 4 to be joined. The current flows downward in the metal layer 2 and flows into the adjacent conductive polymer layer 1 through the electrode layer 5 to be joined. Thereafter, the same current path 6 is repeated.

  As shown in FIG. 1, in the thermoelectric conversion module 100 of one embodiment of the present invention, the conductive polymer layer 1 and the metal layer 2 are directly joined to form an electrical series connection, in other words, a current path between the two. Without using the PEDOT: PSS for the conductive polymer layer 1 and using Ni for the metal layer 2, the current path between the two is formed via the electrode layers 4 and 5 bonded to each other. This is because it is assumed that the contact resistance at the bonding interface between the conductive polymer layer 1 and the metal layer 2 is large, as in the case of the case.

  FIG. 8 shows contact resistances with a plurality of metal materials when PEDOT: PSS is used as the conductive polymer layer 1. Other than Ni, Al is obviously unsuitable as an electrode layer because of its high contact resistance. As the electrode layer, Au, Pt, Ag, C, or Cu can be used. More preferably, Au, Pt, or Ag, which is a metal that has low contact resistance and is difficult to oxidize, can be used as the electrode layer. In addition, “20 nm Au—Ni” in FIG. 8 is a contact resistance when Au having a thickness of 20 nm is formed on Ni on the PEDOT: PSS film. This configuration is the same as the combination of the conductive polymer layer 1 (PEDOT: PSS), the metal layer 2 (Ni), and the electrode layers (Au) 4 and 5 in the thermoelectric conversion module 100 of the embodiment of the present invention shown in FIG. It is.

  As the insulating layer 3, for example, an insulating polymer can be used. As the insulating polymer, for example, liquid glue (PVAL: polyvinyl alcohol) can be used.

  A method for manufacturing the thermoelectric conversion module according to the embodiment of the present invention shown in FIG. 1 will be described with reference to FIGS. In step (a) of FIG. 2, a first metal layer is prepared. As shown in FIG. 3 (a), a conventional thin film forming technique such as vacuum deposition of an electrode layer (for example, Au) 4 is performed on the surface of the metal layer (for example, Ni foil) 2 by using a mask that first covers an end portion. Form. Next, an insulating layer (insulating polymer, for example, a liquid paste) 3 is formed (for example, coated) using a mask that covers the electrode layer. Thereafter, the insulating polymer is fixed and flattened by heating for a predetermined time (for example, several tens of minutes at 50 to 100 degrees). In the present invention, the form in which the insulating layer 3 and the electrode layer 4 are formed on the surface of the metal foil 2 (A in FIG. 3) is referred to as a first metal layer.

  In step (b) of FIG. 2, a second metal layer is prepared. As shown in FIG. 3B, electrode layers (for example, Au) 4 and 5 and insulating layers (insulating properties) are formed on both surfaces (front and back) of a metal layer (for example, Ni foil) 2 by the same method as in step (a). A polymer (for example, a liquid paste) 3 is formed (for example, coated). At this time, the electrode layer 4 on the front surface of the metal layer (for example, Ni foil) 2 and the electrode layer 5 on the back surface are positioned at opposite ends. In the present invention, the form in which the insulating layer 3 and the electrode layers 4 and 5 are formed on both surfaces of the metal foil 2 (B in FIG. 3) is referred to as a second metal layer.

  In step (c) of FIG. 2, the conductive polymer layer 1 is prepared. For example, when PEDOT: PSS is used as the conductive polymer layer 1, a cast method is used to apply an aqueous dispersion of PEDOT: PSS, for example, with 3% EG applied on the substrate, and at a predetermined temperature. Allow to dry slowly (eg, tens of hours at 100 degrees or less). The PEDOT: PSS (EG) film after drying is peeled off from the substrate to obtain a PEDOT: PSS (EG) film 1 having the same size as the metal foil (for example, Ni foil) 2 as shown in FIG. .

  In step (d) of FIG. 2, as shown in FIG. 3 (d), the second metal layer B and the conductive polymer layer (for example, PEDOT: PSS (EG) film) 1 prepared in step (c) are formed. A laminated structure in which the conductive polymer layers 1 are alternately laminated is formed. The number of the second metal layer B and the conductive polymer layer 1 to be laminated can be determined according to the desired thermoelectric output (thermoelectromotive force). The laminated structure is processed and shaped as necessary, and the overall size and the flatness of the cross section (the upper surface and the lower surface in FIG. 3D) are adjusted.

    In step (e) of FIG. 2, as shown in FIG. 3 (e), the first metal layer A is bonded to both end faces of the laminated structure created in step (d). At this time, the first metal layer A is bonded so that the metal layer 2 of the first metal layer A is on the outside (surface). The bonded structure is heated at a predetermined temperature while being pressed at a predetermined pressure (for example, 100 to 300 kgf, 80 to 150 degrees for several tens of minutes) to obtain a thermoelectric conversion module.

  The thermoelectric conversion module 100 of FIG. 1 was actually produced using the manufacturing method (process) shown in FIG. A thermoelectric conversion module 100 composed of 10 units (group) was produced with the conductive polymer layer 1 and the second metal layer B as one unit (group). A PEDOT: PSS (EG) film (thickness: 50 to 100 μm) is used as the electroconductive polymer layer 1, a Ni foil (thickness: about 5 μm) is used as the metal layer 2, and a liquid paste (PVAL: Polyvinyl alcohol) was used, and Au (20 to 30 nm) was used as the electrode layer 4. The overall size is 22 mm × 22 mm and the thickness is 2 mm. FIG. 4 shows the appearance of the produced thermoelectric conversion module. The Ni foil forming the outer layer is visible on the surface of FIG.

  As shown in FIG. 1 (c), the thermoelectric power (mV) was measured by giving a temperature difference ΔT (K) up and down to the produced thermoelectric conversion module 100. FIG. 5 shows the result. It can be seen that the thermoelectromotive force (mV) increases almost linearly as the temperature difference ΔT (K) increases. The Seebeck coefficient S at this time was 332.7 μV / K.

  FIG. 6 shows the measurement result of the current-voltage (IV) characteristics of the thermoelectric conversion module 100 produced. From the linearity of the figure, it was found that it was an ohmic junction, and its resistance value R was 4.6Ω.

FIG. 7 shows the relationship between the output voltage and output power of the thermoelectric conversion module 100 produced. As the temperature difference ΔT (K) increases to 10K, 30K, and 50K, the output voltage (mV) and output power (μW) increase, and when ΔT = 50K, the maximum power P = 10 μW / 0.44 cm ² (22.7 μW). / Cm ² ) could be obtained. That is, it was found that an output power density of ²⁰ μW / cm ² or more can be obtained. It was also found that an output voltage V = 15 mV can be obtained at ΔT = 50K.

Embodiments of the present invention have been described with reference to the drawings. However, the present invention is not limited to these embodiments. Furthermore, the present invention can be implemented in variously modified, modified, and modified forms based on the knowledge of those skilled in the art without departing from the spirit of the present invention.

  Since the thermoelectric conversion module of the present invention is small and lightweight, it can be used in a wide range of industries including exhaust heat recovery around us.

DESCRIPTION OF SYMBOLS 1 Conductive polymer layer 2 Metal layer 3 Insulating layer 4, 5 Electrode layer 6 Current path 100 Thermoelectric conversion module

Claims (10)

Between the two metal layers located at both ends, a conductive polymer layer having a P-type thermoelectric property and a metal layer are alternately laminated without gaps,
An insulating layer and an electrode layer are bonded to both surfaces of the conductive polymer layer,
The electrode layer is positioned at a first end of the surface of the conductive polymer layer and a second end opposite to the first end of the back surface, and the conductive polymer layer and the metal layer Is a thermoelectric conversion module that is electrically connected via the electrode layer.   The conductive polymer layer is made of a PEDOT: PSS film, the metal layer is made of Ni, and the electrode layer is made of one or more selected from Au, Pt, Ag, Cu, and C. The thermoelectric conversion module according to claim 1.   The thermoelectric conversion module according to claim 2, wherein the insulating layer is made of an insulating polymer layer.   During power generation, a current flowing in the conductive polymer layer in the first direction flows into the adjacent metal layer through the electrode layer to be joined, and the metal layer is in a second direction opposite to the first direction. The thermoelectric conversion module according to claim 1, wherein A method for manufacturing a thermoelectric conversion module, comprising:
Preparing a first metal layer in which an electrode layer is formed at an end of the surface and an insulating layer is formed in a region other than the electrode layer on the surface;
Preparing a second metal layer in which electrode layers are formed at both ends and an insulating layer is formed in a region other than the electrode layers on both surfaces, the end portions on both surfaces being mutually A step located on the opposite side;
Preparing at least two or more conductive polymer layers, and forming a laminated structure in which the second metal layer is bonded between two adjacent conductive polymer layers;
Bonding the first metal layer to the surface of each of the conductive polymer layers at both ends of the laminated structure so that the electrode layer and the insulating layer on the surface are in contact with each other.   The manufacturing method according to claim 5, wherein the conductive polymer layer is made of a PEDOT: PSS film. Preparing the first metal layer and preparing the second metal layer,
Forming a metal layer composed of one or more selected from Au, Pt, Ag, Cu, and C at the end of the surface of the Ni foil;
Forming an insulating polymer layer in a region other than the electrode layer on the surface of the Ni foil.   The manufacturing method according to claim 7, further comprising a step of pressurizing and heating the laminated structure after joining the first metal layer.   The step of forming a metal layer on an end portion of the surface of the Ni foil includes one or more metals selected from Au, Pt, Ag, Cu, and C using a mask on the surface of the Ni foil. The manufacturing method of Claim 7 including the step which vapor-deposits.   The method according to claim 9, wherein the step of forming the insulating polymer layer in a region other than the electrode layer on the surface of the Ni foil includes a step of applying a liquid paste to the region and heating the region.

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