Thermoelectric conversion module

Abstract

This thermoelectric conversion module comprises: a substrate having a first main surface, and a second main surface positioned on the side opposite the first main surface; a thermoelectric conversion unit positioned on the first main surface; and a capacitor that is disposed on the second main surface so as to be able of perform heat exchange with the thermoelectric conversion unit through the substrate, and that is electrically connected to the thermoelectric conversion unit. The substrate, the thermoelectric conversion unit, and the capacitor overlap each other in the thickness direction of the substrate. The capacitor includes: a plurality of electrodes that are mutually laminated in the thickness direction; and a dielectric that is heat resistant and fills in gaps between the plurality of electrodes.

Description

thermoelectric conversion module

[0001] The present disclosure relates to a thermoelectric conversion module.

[0002] Thermoelectric conversion elements are sometimes used to generate electricity using geothermal energy or factory waste heat. Patent Document 1 below discloses an embodiment in which flexible substrates having patterned layers made of a resin layer and a metal layer are provided on both sides of a thermoelectric conversion module having P-type thermoelectric element material and N-type thermoelectric element material. In Patent Document 1 below, the metal layer included in one flexible substrate overlaps one electrode included in the thermoelectric conversion module, and the metal layer included in the other flexible substrate overlaps the other electrode included in the thermoelectric conversion module. In this embodiment, one flexible substrate is kept in a high-temperature state and the other flexible substrate is kept in a low-temperature state, thereby generating a temperature difference in the surface direction of the thermoelectric conversion module. This generates an electromotive force in the thermoelectric conversion module.

[0003] Patent No. 4895293

[0004] For example, in some electronic devices that use a thermoelectric conversion module as a power source, such as that described in Patent Document 1, the thermoelectric conversion module is connected to a capacitor for storing electricity. However, simply arranging the thermoelectric conversion module and the capacitor side by side can result in an increase in the size of the electronic device.

[0005] An object of one aspect of the present disclosure is to provide a thermoelectric conversion module that can prevent the power source from becoming large while maintaining its function as a power source.

[0006] A thermoelectric conversion module according to one aspect of the present disclosure is as follows: [1] A thermoelectric conversion module comprising: a substrate having a first main surface and a second main surface located opposite to the first main surface; a thermoelectric conversion unit located on the first main surface; and a capacitor located on the second main surface to be able to exchange heat with the thermoelectric conversion unit via the substrate and electrically connected to the thermoelectric conversion unit, wherein the substrate, the thermoelectric conversion unit, and the capacitor overlap each other in a thickness direction of the substrate, and the capacitor has a plurality of electrodes stacked on top of each other in the thickness direction, and a dielectric that fills gaps between the plurality of electrodes and exhibits heat resistance. [2] The thermoelectric conversion module according to [1], wherein the capacitor is flexible. [3] The thermoelectric conversion module according to [1] or [2], further comprising a heat insulating member located on the second main surface, wherein the thermoelectric conversion unit has p-type thermoelectric conversion elements and n-type thermoelectric conversion elements aligned along a first direction perpendicular to the thickness direction, wherein first ends of the p-type thermoelectric conversion elements in the first direction contact first ends of the n-type thermoelectric conversion elements in the first direction and overlap the heat insulating member in the thickness direction, wherein the capacitors include a first capacitor and a second capacitor adjacent to each other in the first direction via the heat insulating member and in contact with the second main surface, wherein the first capacitor overlaps second ends of the n-type thermoelectric conversion elements in the first direction in the thickness direction, and the second capacitor overlaps second ends of the p-type thermoelectric conversion elements in the first direction in the thickness direction. [4] The thermoelectric conversion module according to [3], further comprising a sheet capacitor overlapping the first capacitor and the second capacitor in the thickness direction and electrically connected to the thermoelectric conversion unit. [5] The thermoelectric conversion module according to [4], wherein the sheet capacitor is in contact with the first capacitor and the second capacitor and is spaced apart from the heat insulating member.[6] The thermoelectric conversion module according to [1] or [2], further comprising: a heat insulating member located on the second main surface; and a first heat conducting portion and a second heat conducting portion adjacent to each other along a first direction perpendicular to the thickness direction via the heat insulating member, wherein the thermoelectric conversion portion has p-type thermoelectric conversion elements and n-type thermoelectric conversion elements aligned along the first direction, a first end portion of the p-type thermoelectric conversion element in the first direction contacts a first end portion of the n-type thermoelectric conversion element in the first direction and overlaps the heat insulating member in the thickness direction, the first heat conducting portion overlaps a second end portion of the n-type thermoelectric conversion element in the first direction in the thickness direction, and the second heat conducting portion overlaps a second end portion of the p-type thermoelectric conversion element in the first direction in the thickness direction, and the capacitor is capable of exchanging heat with the thermoelectric conversion portion via the substrate and at least one of the first heat conducting portion and the second heat conducting portion. [7] The thermoelectric conversion module according to [6], wherein the capacitor is a sheet capacitor overlapping the first thermally conductive portion and the second thermally conductive portion in the thickness direction, and the sheet capacitor is in contact with the first thermally conductive portion and the second thermally conductive portion and spaced apart from the heat insulating member. [8] The thermoelectric conversion module according to any of [1] to [7], further comprising a connection portion located on the substrate and electrically connected to both the thermoelectric conversion portion and the capacitor. [9] The thermoelectric conversion module according to any of [1] to [8], wherein the thermal conductivity of the plurality of electrodes and the thermal conductivity of the dielectric are each 3 W / mK or higher.

[0007] According to one aspect of the present disclosure, it is possible to provide a thermoelectric conversion module that can prevent the power source from becoming large while maintaining its function as a power source.

[0008] FIG. 1A is a schematic plan view showing a thermoelectric conversion module according to an embodiment, and FIG. 1B is a schematic bottom view showing a thermoelectric conversion module according to an embodiment. FIG. 2A is an enlarged view of a portion (the area surrounded by a dashed line) of FIG. 1A, and FIG. 2B is a cross-sectional view taken along line IIb-IIb of FIG. 2A. FIG. 3A is a cross-sectional view taken along line IIIa-IIIa of FIG. 1A, and FIG. 3B is a cross-sectional view taken along line IIIb-IIIb of FIG. 1A. FIG. 4A is a schematic bottom view showing a thermoelectric conversion module according to a first modified example, and FIG. 4B is a cross-sectional view taken along line IVb-IVb of FIG. 4A. FIG. 5 is a cross-sectional view of a main portion of a thermoelectric conversion module according to a second modified example.

[0009] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In the following description, identical elements or elements having the same functions will be designated by the same reference numerals, and duplicated explanations will be omitted. In this specification, the term "same" and similar words are not limited to "completely same."

[0010] First, the configuration of the thermoelectric conversion module according to this embodiment will be described with reference to Figures 1 and 2. Figure 1(a) is a schematic plan view showing the thermoelectric conversion module according to this embodiment, and Figure 1(b) is a schematic bottom view showing the thermoelectric conversion module according to this embodiment. Figure 2(a) is an enlarged view of a portion (the area surrounded by the dashed line) of Figure 1(a). Figure 2(b) is a cross-sectional view taken along line IIb-IIb of Figure 2(a).

[0011] The thermoelectric conversion module 1 shown in FIGS. 1A and 1B is a device capable of generating electricity by externally supplying heat. The thermoelectric conversion module 1 is a so-called in-plane device. Therefore, the thermoelectric conversion module 1 tends to be more easily processed and flexible than, for example, π-type elements (cross-plane elements). Therefore, the thermoelectric conversion module 1 can be installed, for example, along the side of a cylindrical pipe used for recovering factory exhaust heat. In other words, the thermoelectric conversion module 1 can be easily installed in various locations. Therefore, the thermoelectric conversion module 1 is used, for example, as a power source for electronic devices such as plant sensors that utilize exhaust heat. In addition, the contact resistance between the thermoelectric conversion material and electrodes included in the thermoelectric conversion module 1 also tends to be lower than that of π-type modules. Hereinafter, the temperatures of each component of the thermoelectric conversion module 1 are measured under natural air convection conditions.

[0012] The thermoelectric conversion module 1 has a substrate 2, a plurality of thermoelectric conversion groups 3, a plurality of conductive parts 4, a plurality of heat conducting parts 5, a plurality of heat insulating members 6, and a connection part 7. At least one of the substrate 2, the plurality of thermoelectric conversion groups 3, the plurality of conductive parts 4, the plurality of heat conducting parts 5, the plurality of heat insulating members 6, and the connection part 7 exhibits flexibility.

[0013] The substrate 2 is a sheet member made of a resin that exhibits heat resistance and flexibility, and has, for example, a substantially flat plate shape. The resin that constitutes the substrate 2 is, for example, a (meth)acrylic resin, a (meth)acrylonitrile resin, a polyamide resin, a polycarbonate resin, a polyether resin, a polyester resin, an epoxy resin, an organosiloxane resin, a polyimide resin, a polysulfone resin, or the like. The thickness of the substrate 2 is, for example, 5 μm or more and 50 μm or less. The thermal conductivity of the substrate 2 is, for example, 0.1 W / mK (0.1 watts per meter per Kelvin, and 0.1 W×m －１ ×K －１ When the thermal conductivity of the substrate 2 is 0.3 W / mK or less, a temperature difference may occur inside the thermoelectric conversion group 3. The thermal conductivity of the substrate 2 is measured by a steady-state method or a non-steady-state method.

[0014] The substrate 2 has a first main surface 2a and a second main surface 2b located on the opposite side of the first main surface 2a. The first main surface 2a and the second main surface 2b are planes that intersect with the direction along the thickness of the substrate 2. The shapes of the first main surface 2a and the second main surface 2b are not particularly limited, and may be, for example, polygonal, circular, or elliptical. Hereinafter, the direction along the thickness of the substrate 2 will be simply referred to as the thickness direction D1. Viewing from the thickness direction D1 corresponds to a planar view. Furthermore, directions perpendicular to the thickness direction D1 are referred to as the first direction D2 and the second direction D3. The second direction D3 is a direction perpendicular to both the thickness direction D1 and the first direction D2.

[0015] A thermoelectric conversion region R1 and two conductive regions R2 are defined on the first main surface 2a. A plurality of thermoelectric conversion groups 3 are provided in the thermoelectric conversion region R1. A plurality of conductive portions 4 are provided in each conductive region R2. The thermoelectric conversion region R1 is located between the two conductive regions R2 in the first direction D2. The larger the proportion of the first main surface 2a occupied by the thermoelectric conversion region R1, the higher the output of the thermoelectric conversion module 1 tends to be. In a plan view, the proportion of the area occupied by the thermoelectric conversion region R1 of the first main surface 2a is, for example, 50% to 90%. Furthermore, in a plan view, the proportion of the area occupied by the two conductive regions R2 of the first main surface 2a is, for example, 5% to 30%. In this case, the thermoelectric conversion module 1 can produce good output while reliably forming conductive paths connecting the thermoelectric conversion groups 3.

[0016] Openings O1 and O2 functioning as through holes are provided in the substrate 2. Each of the openings O1 and O2 is an opening portion extending from the first main surface 2a to the second main surface 2b. The conductive portion 4 and the connection portion 7 are electrically connected via a conductive material provided on the surface of the openings O1 and O2 (details will be described later).

[0017] Each of the thermoelectric conversion groups 3 is capable of generating electricity when heat is supplied from the outside and is located on the first main surface 2a. The thermoelectric conversion groups 3 extend along the first direction D2 and are arranged along the second direction D3. Each of the thermoelectric conversion groups 3 has a strip shape when viewed from the thickness direction D1. The thermoelectric conversion groups 3 are spaced apart from each other but electrically connected to each other in series. In the first direction D2, one end of each thermoelectric conversion group 3 is connected to one of the conductive parts 4 included in one conductive region R2, and the other end of each thermoelectric conversion group 3 is connected to one of the conductive parts 4 included in the other conductive region R2. As shown in FIG. 2A, each of the thermoelectric conversion groups 3 has multiple thermoelectric conversion units 11. In this embodiment, each thermoelectric conversion group 3 has ten thermoelectric conversion units 11, but this is not limited to this. In each thermoelectric conversion group 3, the multiple thermoelectric conversion units 11 are arranged along the first direction D2. Two thermoelectric conversion units 11 adjacent to each other in the first direction D2 are in contact with each other and are connected in series.

[0018] Each of the multiple thermoelectric conversion units 11 is a flexible portion of the thermoelectric conversion module 1 where thermoelectric conversion is performed. The shape of the thermoelectric conversion unit 11 in a plan view is not particularly limited, and may be, for example, a polygonal, circular, or elliptical shape. The p-type thermoelectric conversion elements 21 and the n-type thermoelectric conversion elements 22 have the same shape, but are not limited to this. Each thermoelectric conversion unit 11 has the p-type thermoelectric conversion elements 21 and the n-type thermoelectric conversion elements 22 arranged along the first direction D2. In each thermoelectric conversion unit 11, the first end 21 a of the p-type thermoelectric conversion element 21 in the first direction D2 and the first end 22 a of the n-type thermoelectric conversion element 22 in the first direction D2 are in contact with each other. In each thermoelectric conversion unit 11, the second end 21b of the p-type thermoelectric conversion element 21 in the first direction D2 is located at one end of the corresponding thermoelectric conversion unit 11, and the second end 22b of the n-type thermoelectric conversion element 22 in the first direction D2 is located at the other end of the corresponding thermoelectric conversion unit 11. In two thermoelectric conversion units 11 adjacent to each other in the first direction D2, the second end 21b of the p-type thermoelectric conversion element 21 included in one thermoelectric conversion unit 11 and the second end 22b of the n-type thermoelectric conversion element 22 included in the other thermoelectric conversion unit 11 come into contact with each other.

[0019] In each of the plurality of thermoelectric conversion groups 3, the p-type thermoelectric conversion elements 21 and the n-type thermoelectric conversion elements 22 are arranged alternately in the first direction D2. In this embodiment, the p-type thermoelectric conversion elements 21 and the n-type thermoelectric conversion elements 22 are arranged alternately in the second direction D3.

[0020] The p-type thermoelectric conversion element 21 is provided on the first main surface 2a of the substrate 2 and is in contact with the n-type thermoelectric conversion element 22. The thickness T1 of the p-type thermoelectric conversion element 21 is, for example, 3 μm or more and 30 μm or less. When the thickness T1 is 3 μm or more, the electrical resistance of the p-type thermoelectric conversion element 21 can be effectively reduced. When the thickness T1 is 30 μm or less, a temperature gradient can be easily formed inside the p-type thermoelectric conversion element 21. The thickness T1 may be 5 μm or more, 8 μm or more, 10 μm or more, 25 μm or less, 20 μm or less, or 15 μm or less. The length L1 of the p-type thermoelectric conversion element 21 in the first direction D2 is, for example, 2 mm or more and 10 mm or less. In this case, a temperature gradient can be easily formed inside the p-type thermoelectric conversion element 21. The length of the p-type thermoelectric conversion element 21 in the second direction D3 is, for example, 5 mm or more and 30 mm or less. In this case, a sufficient number of thermoelectric conversion portions 11 can be formed on the first main surface 2a. The thermal conductivity of the p-type thermoelectric conversion element 21 in the in-plane direction is, for example, 0.01 W / mK or more and 40.0 W / mK or less. The thermal conductivity of the p-type thermoelectric conversion element 21 in the in-plane direction is measured, for example, by an optical alternating current method or a 3 omega method. The p-type thermoelectric conversion element 21 is formed, for example, by various dry or wet methods. Wet methods include, for example, a doctor blade method, a dip coating method, a spray coating method, a spin coating method, and an inkjet method.

[0021] The p-type thermoelectric conversion element 21 is, for example, a p-type semiconductor layer. The p-type thermoelectric conversion element 21 includes, for example, carbon nanotubes (CNTs) and a conductive resin different from the carbon nanotubes. The carbon nanotubes are p-type. The carbon nanotubes may be single-walled, double-walled, or multi-walled. From the viewpoint of the electrical conductivity of the p-type thermoelectric conversion element 21, single-walled carbon nanotubes (SWCNTs) may be used. The proportion of single-walled carbon nanotubes relative to the total amount of carbon nanotubes may be 25% by mass or more, 50% by mass or more, or 100% by mass. The diameter of the single-walled carbon nanotubes is not particularly limited, but may be, for example, 20 nm or less, 10 nm or less, or 3 nm or less. The lower limit of the diameter of the single-walled carbon nanotubes is also not particularly limited, but may be 0.4 nm or more, or 0.5 nm or more. The thermal conductivity of the carbon nanotubes is, for example, 30 W / mK or more and 40 W / mK or less.

[0022] In this specification, the diameter of a single-walled carbon nanotube is determined by Raman spectroscopy to be 100 to 300 cm －１ The wave number of the peak that appears in －１ )), the diameter can be calculated using the formula "diameter (nm) = 248 / ω". The G / D ratio in laser Raman spectroscopy is known as a method for evaluating single-walled carbon nanotubes. In this embodiment, the single-walled carbon nanotubes may have a G / D ratio of 10 or more, or 20 or more, in laser Raman spectroscopy at a wavelength of 532 nm. By using such single-walled carbon nanotubes, a p-type thermoelectric conversion element 21 with even better electrical conductivity tends to be obtained. The upper limit of the G / D ratio is not particularly limited, and may be 500 or less, or 300 or less.

[0023] The content of carbon nanotubes in the p-type thermoelectric conversion element 21 may be, for example, 20 parts by mass or more, 30 parts by mass or more, 40 parts by mass or more, 99 parts by mass or less, 95 parts by mass or less, or 90 parts by mass or less, per 100 parts by mass of the material (p-type thermoelectric conversion material) constituting the p-type thermoelectric conversion element 21.

[0024] The conductive resin of this embodiment is not particularly limited, and known conductive resins can be used without particular limitation. Examples of conductive resins include polyaniline-based conductive resins, polythiophene-based conductive resins, polypyrrole-based conductive resins, polyacetylene-based conductive resins, polyphenylene-based conductive resins, and polyphenylene vinylene-based conductive resins. Examples of polythiophene-based conductive resins include poly(3,4-ethylenedioxythiophene) (PEDOT). In this embodiment, the conductive resin includes PEDOT and an electron acceptor. In this case, the electrical conductivity of the p-type thermoelectric conversion element 21 tends to be higher. Examples of the electron acceptor include polystyrene sulfonic acid, polyvinyl sulfonic acid, poly(meth)acrylic acid, polyvinyl sulfonic acid, toluenesulfonic acid, dodecylbenzenesulfonic acid, camphorsulfonic acid, bis(2-ethylhexyl) sulfosuccinate, chlorine, bromine, iodine, phosphorus pentafluoride, arsenic pentafluoride, boron trifluoride, hydrogen chloride, sulfuric acid, nitric acid, tetrafluoroboric acid, perchloric acid, iron(III) chloride, tetracyanoquinodimethane, etc. From the viewpoint of the electrical conductivity of the p-type thermoelectric conversion element 21, the electron acceptor may be polystyrene sulfonic acid (PSS).

[0025] The carbon nanotubes and the conductive resin may be aggregated in the p-type thermoelectric conversion element 21. The p-type thermoelectric conversion element 21 may include a porous structure in which the carbon nanotubes are bonded to each other by the conductive resin.

[0026] The n-type thermoelectric conversion elements 22 are provided on the first main surface 2a of the substrate 2 and are in contact with the p-type thermoelectric conversion elements 21. The thickness of the n-type thermoelectric conversion elements 22 is the same as or substantially the same as the thickness T1 of the p-type thermoelectric conversion elements 21. The length of the n-type thermoelectric conversion elements 22 in the first direction D2 is the same as or substantially the same as the length L1 of the p-type thermoelectric conversion elements 21. The length of the n-type thermoelectric conversion elements 22 in the second direction D3 is, for example, 2 mm or more and 10 mm or less. In this case, a sufficient number of thermoelectric conversion sections 11 can be formed on the first main surface 2a. The thermal conductivity of the n-type thermoelectric conversion elements 22 in the in-plane direction is, for example, 0.01 W / mK or more and 40.0 W / mK or less. The thermal conductivity of the n-type thermoelectric conversion elements 22 in the in-plane direction is measured, for example, by an optical alternating current method or a 3 omega method. The n-type thermoelectric conversion element 22 is formed by, for example, various dry or wet methods, similar to the p-type thermoelectric conversion element 21 .

[0027] The n-type thermoelectric conversion element 22 is, for example, an n-type semiconductor layer. The n-type thermoelectric conversion element 22 includes, for example, a composite of multiple organic materials or a composite of an inorganic material and an organic material. In this embodiment, the n-type thermoelectric conversion element 22 is a portion of the p-type thermoelectric conversion element 21 that exhibits n-type conductivity by containing a dopant. Therefore, the n-type thermoelectric conversion element 22 includes carbon nanotubes, a conductive resin, and a dopant. In this embodiment, the dopant refers to a substance that changes the Seebeck coefficient of the portion doped with the dopant. "Changing the Seebeck coefficient" refers to decreasing the Seebeck coefficient value or changing the Seebeck coefficient value from a positive value to a negative value. A thermoelectric conversion material that exhibits a positive Seebeck coefficient has p-type conductivity, and a thermoelectric conversion material that exhibits a negative Seebeck coefficient has n-type conductivity.

[0028] The dopant of this embodiment contains, for example, a coordination compound that can dissociate into an anion (hereinafter simply referred to as "anion"), which is a complex ion, and an alkali metal cation (hereinafter simply referred to as "cation"), and a cation scavenger (hereinafter simply referred to as "scavenger"). Within the n-type thermoelectric conversion element 22, at least a portion of the coordination compound may be dissociated into the anion and the cation. In this case, the cation may be captured by the scavenger. The dopant may contain multiple types of at least one of the coordination compound and the scavenger. The Seebeck coefficient changes in the portion of the p-type thermoelectric conversion element 21 that contains the dopant. This results in the formation of an n-type thermoelectric conversion element 22 in the portion.

[0029] The reason for the above-described effect is not particularly limited, but one possible reason is that the scavenger contained in the dopant captures cations, dissociating anions, and the anions convert the carriers of the carbon nanotubes from holes to electrons. In this embodiment, the anions are complex ions with a metal atom at their center, and it is believed that the interaction between the metal atom and the carbon nanotubes significantly converts the anions to n-type. Another possible reason for the above-described effect is that the complex ions have a large ionic size, which allows them to dissociate easily with the cations captured by the scavenger. In the dopant of this embodiment, the anions are complex ions. Therefore, the n-type thermoelectric conversion element 22 contains metal atoms derived from the complex ions. Therefore, in this embodiment, the metal atoms remaining in the n-type thermoelectric conversion element 22 can function as an antioxidant.

[0030] The complex ion (anion) obtained by dissociation of the coordination compound may be selected from the group consisting of ferrocyanide ion, ferricyanide ion, tetrachloroferrate(III) ion, tetrachloroferrate(II) ion, tetracyanonickelate(II) ion, tetrachloronickelate(II) ion, tetracyanocobaltate(II) ion, tetrachlorocobaltate(II) ion, tetracyanocuprate(I) ion, tetrachlorocuprate(II) ion, hexacyanochromate(III) ion, tetrahydroxidezincate(II) ion, and tetrahydroxidealuminate(III) ion. Among these, ferrocyanide ion may be selected. When the anion is ferrocyanide ion, a material with better properties can be obtained. Furthermore, when the anion is ferrocyanide ion, the iron atoms remaining in the n-type thermoelectric conversion element 22 function favorably as an antioxidant, which tends to further suppress changes in physical properties over time and improve storage stability.

[0031] The anion may include an iron atom. That is, the coordination compound may include an iron atom. In this case, the anion may be selected from the group consisting of, for example, a ferrocyanide ion, a ferricyanide ion, a tetrachloroferrate(III) ion, and a tetrachloroferrate(II) ion. From the viewpoint of the characteristics of the n-type thermoelectric conversion element 22, the anion including an iron atom may be a ferrocyanide ion. From the viewpoint of the antioxidant effect, the content of iron atoms in the n-type thermoelectric conversion element 22 may be 0.001% by mass or more and 15% by mass or less, 0.005% by mass or more and 12% by mass or less, or 0.01% by mass or more and 10% by mass or less. The content of iron atoms in the n-type thermoelectric conversion element 22 indicates a value measured, for example, by ICP atomic emission spectrometry.

[0032] The coordination compound may be a complex salt. Examples of the complex salt include potassium ferrocyanide, sodium ferrocyanide, potassium ferricyanide, sodium ferricyanide, potassium tetrachloroferrate(III), sodium tetrachloroferrate(III), potassium tetrachloroferrate(II), and sodium tetrachloroferrate(II). The complex salt may be a hydrate.

[0033] Examples of alkali metal cations obtained by dissociation of the coordination compound include sodium ions, potassium ions, and lithium ions. The coordination compound may contain at least one of a ferrocyanide compound and a ferricyanide compound.

[0034] The cation scavenger is not particularly limited as long as it has the ability to capture cations. Examples of cation scavenger include crown ether compounds, cyclodextrin, calixarene, ethylenediaminetetraacetic acid, porphyrin, phthalocyanine, and derivatives thereof. In this embodiment, the cation scavenger is a crown ether compound. Examples of crown ether compounds include 15-crown-5-ether, 18-crown-6-ether, 12-crown-4-ether, benzo-18-crown-6-ether, benzo-15-crown-5-ether, and benzo-12-crown-4-ether. The ring size of the crown ether used as the scavenger can be selected according to the size of the metal ion to be captured. For example, when the metal ion is a potassium ion, the crown ether compound may be an 18-membered ring crown ether. When the metal ion is a sodium ion, the crown ether compound may be a 15-membered ring crown ether. When the metal ion is a lithium ion, the crown ether compound may be a 12-membered ring crown ether.

[0035] The crown ether compound may contain a benzene ring. In this case, the stability of the crown ether compound may be improved. Examples of crown ether compounds having a benzene ring include benzo-18-crown-6-ether, benzo-15-crown-5-ether, and benzo-12-crown-4-ether.

[0036] Cation content CA １ The content of the scavenger CA ２ The molar ratio of CA ２ / CA １ ) may be 0.1 or more and 5 or less, 0.3 or more and 3 or less, or 0.5 or more and 2 or less.

[0037] In each of the multiple thermoelectric conversion units 11, the mass ratio of carbon nanotubes to the total mass of the thermoelectric conversion units 11 is, for example, 30% or more and 70% or less. When the mass ratio is 30% or more, the thermoelectric conversion units 11 can have good electrical conductivity. When the mass ratio is 70% or less, the temperature difference within the thermoelectric conversion units 11 is likely to be large. The mass ratio may be 35% or more, 40% or more, 45% or more, or 50% or more. The mass ratio may be 65% or less, 60% or less, or 55% or less. The mass ratio of carbon nanotubes to the total mass of the p-type thermoelectric conversion elements 21 may be 30% or more and 70% or less, and the mass ratio of carbon nanotubes to the total mass of the n-type thermoelectric conversion elements 22 may be 30% or more and 70% or less. In each of the plurality of thermoelectric conversion groups 3, the mass ratio of the carbon nanotubes to the total mass of the thermoelectric conversion group 3 may be 30% or more and 70% or less, or 40% or more and 60% or less. The internal temperature difference of the thermoelectric conversion unit 11, etc. is measured using, for example, thermography.

[0038] Each of the plurality of conductive portions 4 is a conductive portion located on the first principal surface 2a and connected to a corresponding thermoelectric conversion group 3. Each conductive portion 4 may be a semiconductor rather than a conductor. The thickness of each conductive portion 4 is the same as or substantially the same as the thickness T1 of the p-type thermoelectric conversion element 21. The conductivity of each conductive portion 4 may be equal to or greater than the conductivity of the p-type thermoelectric conversion element 21. The thermal conductivity of each conductive portion 4 may be equal to or greater than the thermal conductivity of the p-type thermoelectric conversion element 21. At least some of the plurality of conductive portions 4 may have a single-layer structure or a multilayer structure. For example, at least some of the plurality of conductive portions 4 may have an organic conductive layer and a metal conductive layer located on the organic conductive layer. In this embodiment, the plurality of conductive portions 4 are formed from the same material as the p-type thermoelectric conversion element 21. Therefore, each conductive portion 4 has the same conductivity type (p-type).

[0039] The plurality of conductive portions 4 have first conductive portions 4a that function as terminals for connecting to the external device and second conductive portions 4b that function as conductive paths connecting adjacent thermoelectric conversion groups 3. The plurality of conductive portions 4 have two first conductive portions 4a located within one conductive region R2. In a plan view, one first conductive portion 4a is provided around the opening O1 of the substrate 2, and the other first conductive portion 4a is provided around the opening O2 of the substrate 2.

[0040] The other conductive region R2 is provided with only the second conductive portion 4b. The multiple thermoelectric conversion groups 3 are connected in series to each other via the multiple second conductive portions 4b. Therefore, when the thermoelectric conversion module 1 is performing thermoelectric conversion, current can flow in series from one first conductive portion 4a to the other first conductive portion 4a. For example, one first conductive portion 4a located in one conductive region R2 is connected to one end of the thermoelectric conversion group 3 in the first direction D2. One second conductive portion 4b located in the other conductive region R2 is connected to the other end of the thermoelectric conversion group 3 in the first direction D2.

[0041] The multiple heat conductive portions 5 are portions exhibiting a higher thermal conductivity than the substrate 2 and are located on the second main surface 2b. Each heat conductive portion 5 is directly or indirectly fixed to the second main surface 2b. Therefore, each heat conductive portion 5 is arranged so as to be able to exchange heat with the thermoelectric conversion group 3 (i.e., the thermoelectric conversion portion 11) via the substrate 2. In this embodiment, even if the heat conductive portion 5 is fixed to the second main surface 2b via an adhesive or the like, the heat conductive portion 5 is considered to be in contact with the second main surface 2b. The substrate 2, the thermoelectric conversion group 3, and the heat conductive portion 5 overlap each other in the thickness direction D1. Here, at least a portion of the multiple heat conductive portions 5 overlaps the thermoelectric conversion group 3 (i.e., the thermoelectric conversion portion 11) in the thickness direction D1. More specifically, at least a portion of the multiple heat conductive portions 5 overlaps the edges of the thermoelectric conversion portion 11. On the other hand, each heat conductive portion 5 does not overlap the center of the thermoelectric conversion portion 11. This allows a favorable temperature gradient to be generated inside the thermoelectric conversion unit 11 along the first direction D2. The heat conduction units 5 are spaced apart from one another along the first direction D2 and have a band shape extending along the second direction D3 in a plan view. The shape of each heat conduction unit 5 in a plan view is not particularly limited, and may be, for example, a polygonal shape, a circular shape, an elliptical shape, or the like.

[0042] The length T2 of each heat conductive portion 5 along the thickness direction D1 is, for example, 50 μm or more and 2000 μm or less. The width L2 of each heat conductive portion 5 along the first direction D2 is, for example, 0.5 mm or more and 2.0 mm or less. In these cases, the heat conductive function of each heat conductive portion 5 can be satisfactorily exhibited. Between two adjacent heat conductive portions 5, the spacing S along the first direction D2 is greater than the length L1 of the p-type thermoelectric conversion element 21 in the first direction D2 and the length of the n-type thermoelectric conversion element 22 in the first direction D2, and is 3 mm or more and 15 mm or less. The spacing S may be 4 mm or more, 5 mm or more, 6 mm or more, 12 mm or less, 10 mm or less, or 8 mm or less. Alternatively, the spacing S may be less than 12 mm or less.

[0043] 3A is a cross-sectional view taken along line IIIa-IIIa in FIG. 1A. As shown in FIG. 3A, the heat conducting portion 5 is a stacked capacitor located on the second main surface 2b. The capacitor is a member for storing electricity generated by the thermoelectric conversion portion 11. The heat conducting portion 5 is in contact with the second main surface 2b and is electrically connected to the thermoelectric conversion portion 11. The heat conducting portion 5, which is a capacitor, has a plurality of internal electrodes 5a stacked on top of each other in the thickness direction D1, a dielectric 5b filling gaps between the plurality of internal electrodes 5a, an external electrode 5c connected to a first internal electrode 5a1 included in the plurality of internal electrodes 5a, and an external electrode 5d connected to a second internal electrode 5a2 included in the plurality of internal electrodes 5a.

[0044] Each of the multiple internal electrodes 5a is a sheet-like conductive member having a band shape in a planar view. The greater the number of internal electrodes 5a, the better the power storage performance of the capacitor, which is the thermally conductive portion 5. From the perspective of power storage, the number of internal electrodes 5a included in the thermally conductive portion 5 is, for example, 2 to 30. The spacing between adjacent internal electrodes 5a is adjusted depending on the length T2 of the thermally conductive portion 5 and the number of internal electrodes 5a. Examples of materials used for the internal electrodes 5a include conductive materials (e.g., Al, Ni, Cu, etc.) commonly used for internal electrodes of multilayer capacitors. Each internal electrode 5a is, for example, a vapor deposition, a coated and dried product, or a sintered product of the conductive material. In the multiple internal electrodes 5a, the first internal electrodes 5a1 and the second internal electrodes 5a2 are spaced apart from each other and alternately stacked along the thickness direction D1. Each first internal electrode 5a1 extends from the external electrode 5c to the external electrode 5d in the second direction D3. Each first internal electrode 5a1 is in contact with the external electrode 5c but is spaced apart from the external electrode 5d. Each second internal electrode 5a2 extends from the external electrode 5d toward the external electrode 5c in the second direction D3. Each second internal electrode 5a2 is in contact with the external electrode 5d but is spaced apart from the external electrode 5c.

[0045] The dielectric 5b is the main body of the heat conduction part 5 and is a member having insulating properties and heat resistance. The dielectric 5b is a laminate of multiple dielectric layers. The dielectric layers are integrated with each other. In this case, the dielectric layers may be integrated to the extent that their boundaries are not visible. One of the first internal electrode 5a1 and the second internal electrode 5a2 is provided on each dielectric layer. Multiple internal electrodes 5a are formed by alternately stacking dielectric layers provided with the first internal electrode 5a1 and dielectric layers provided with the second internal electrode 5a2.

[0046] From the viewpoint of maintaining the capacitor's electricity storage performance and preventing damage to the capacitor while functioning as the heat-conducting unit 5, the dielectric 5b may be composed of a heat-resistant inorganic solid or a composite of the inorganic solid and a heat-resistant resin. Heat resistance refers to the property of maintaining the original state (solid state) without melting or decomposing at the heat-resistant temperature described below. The heat-resistant temperature is at least 120°C, and may be 150°C or 180°C. In this case, the function of the capacitor, which is the heat-conducting unit 5, is well exhibited even when the thermoelectric conversion module 1 is placed in a high-temperature environment. On the other hand, film capacitors and aluminum electrolytic capacitors made of resins that do not exhibit heat resistance, such as polypropylene, may be damaged in high-temperature environments. Therefore, it can be said that film capacitors and aluminum electrolytic capacitors cannot be used as the heat-conducting unit 5 according to this embodiment.

[0047] The heat-resistant inorganic solid is, for example, BaTiO ３ system, Ba(Ti,Zr)O ３ system, or (Ba, Ca)TiO ３ The dielectric material 5b is a dielectric material of the inorganic solid type. When the dielectric 5b is made of an inorganic solid, the dielectric 5b is made of, for example, a sintered body of ceramic green sheets containing the dielectric material. This sintered body is a sintered body of a laminate of ceramic green sheets (i.e., a sintered body of a plurality of dielectric layers stacked on top of each other). In this case, the dielectric constant of the dielectric 5b can be increased, thereby improving the electricity storage performance of the capacitor.

[0048] When the dielectric 5b is made of a composite material of an inorganic solid and a heat-resistant resin, the dielectric 5b is made of, for example, a heat-resistant resin in which particles of the inorganic solid are dispersed. In this case, the dielectric 5b exhibits good flexibility, making the heat conduction section 5 less likely to be damaged even when the thermoelectric conversion module 1 is deformed. In addition, the dispersion of the inorganic solid particles can improve the thermal conductivity of the dielectric 5b. From the viewpoints of the dielectric constant, thermal conductivity, and the like, the heat-resistant resin is, for example, a silicone resin. From the viewpoints of preventing chipping of the inorganic solid and the dielectric constant of the dielectric 5b, the mass ratio of the inorganic solid to the heat-resistant resin (inorganic solid:heat-resistant resin) in the composite material is, for example, 20:80 to 90:10.

[0049] The external electrode 5c is one of the external terminals of the capacitor and covers one end of the dielectric 5b in the second direction D3. The external electrode 5c contacts all of the first internal electrodes 5a1. The external electrode 5d is another of the external terminals of the capacitor and covers the other end of the dielectric 5b in the second direction D3. The external electrode 5d contacts all of the second internal electrodes 5a2. Each of the external electrodes 5c, 5d may have a single-layer structure or a multi-layer structure. Each of the external electrodes 5c, 5d includes, for example, a sintered layer, a plated layer, etc. The sintered layer includes at least a metal such as Cu, Ni, or Ag. The plated layer is, for example, a Ni plated layer, etc.

[0050] From the viewpoint of the heat conduction function of the heat conduction portion 5, the thermal conductivity of the heat conduction portion 5 in the thickness direction D1 may be 3 W / mK or more, 5 W / mK or more, or 10 W / mK or more. This allows for good heat transfer to the thermoelectric conversion portion 11 via the multiple heat conduction portions 5 when the thermoelectric conversion module 1 is heated. Additionally, heat can be quickly dissipated from a portion of the thermoelectric conversion portion 11 via the multiple heat conduction portions 5. The thermal conductivity of the heat conduction portion 5 in the thickness direction D1 is measured, for example, by an optical alternating current method or a 3 omega method. From the viewpoint of the heat conduction function of the heat conduction portion 5, the thermal conductivity of the internal electrode 5a, the thermal conductivity of the dielectric 5b, and the thermal conductivity of the external electrodes 5c and 5d may each be 3 W / mK or more. The thermal conductivity may be 5.0 W / mK or more, or 10.0 W / mK or more. Alternatively, when the thermal conductivity of the heat conducting portion 5 in the thickness direction D1 is 3 W / mK or more, any one of the thermal conductivity of the internal electrode 5a, the thermal conductivity of the dielectric 5b, and the thermal conductivity of the external electrodes 5c, 5d may be less than 3 W / mK.

[0051] The multiple heat insulating members 6 are portions exhibiting a thermal conductivity equal to or lower than that of the substrate 2 and are located on the second main surface 2b. Each of the multiple heat insulating members 6 is located between two corresponding heat conductive portions 5 in the first direction D2. The multiple heat insulating members 6 are spaced apart from one another along the first direction D2. The shape of each heat insulating member 6 in plan view is not particularly limited, and may be, for example, a polygonal, circular, or elliptical shape. In this embodiment, each heat insulating member 6 has a strip shape extending along the second direction D3 in plan view and contacts both of the corresponding two heat conductive portions 5. Therefore, in this embodiment, the width of each heat insulating member 6 along the first direction D2 corresponds to the interval S. Additionally, both ends of the heat insulating member 6 in the second direction D3 are aligned with both ends of the heat conductive portions 5, but this is not limited thereto. The length T3 of each heat insulating member 6 along the thickness direction D1 is shorter than the length T2 of each heat conductive portion 5. For example, the length T3 is 80% or less, or 70% or less of the length T2. In this case, the heat insulating member 6 is less likely to peel off from the substrate 2 when the thermoelectric conversion module 1 is deformed.

[0052] At least a portion of each of the multiple heat insulating members 6 overlaps the center of the corresponding thermoelectric conversion unit 11 in the thickness direction D1. In other words, in each thermoelectric conversion unit 11, the first end 21a of the p-type thermoelectric conversion element 21 and the first end 22a of the n-type thermoelectric conversion element 22 overlap at least a portion of the corresponding heat insulating member 6 in the thickness direction D1. This stabilizes the temperature at the center of each thermoelectric conversion unit 11, which tends to stably generate a temperature gradient inside the thermoelectric conversion unit 11 along the first direction D2. Therefore, the range of variation in the temperature difference inside each thermoelectric conversion unit 11 over a predetermined period can be, for example, 2.5°C or less, 2.0°C or less, or 1.0°C or less. The range of variation in the temperature difference of the thermoelectric conversion unit 11 can be obtained by measuring the changes over time in each of the high-temperature region of the thermoelectric conversion unit 11 (for example, the center or one of both ends of the thermoelectric conversion unit 11 in the first direction D2) and the low-temperature region of the thermoelectric conversion unit 11 (for example, the center or the other of both ends of the thermoelectric conversion unit 11 in the first direction D2). The predetermined period is not particularly limited, but is, for example, from 10 seconds to 100 hours.

[0053] Each heat insulating member 6 includes, for example, cellulose nanofiber (CNF), silica aerogel, or resin (e.g., silicone resin). Each heat insulating member 6 may be a foam. The thermal conductivity of each heat insulating member 6 is, for example, 0.01 W / mK or more and 0.1 W / mK or less. The thermal conductivity may be 0.02 W / mK or more, 0.03 W / mK or more, 0.08 W / mK or less, or 0.05 W / mK or less. In this embodiment, the thermal conductivity of each heat insulating member 6 is, for example, 0.02 W / mK or more and 0.05 W / mK or less, but is not limited to this.

[0054] 2A, one of the two heat conductive portions 5 (first heat conductive portion) is referred to as a first capacitor C1, and the other heat conductive portion 5 (second heat conductive portion) located adjacent to the first capacitor C1 along the first direction D2 via the heat insulating member 6 is referred to as a second capacitor C2. In this case, in the thickness direction D1, the first capacitor C1 overlaps one end of one thermoelectric conversion portion 11 in the first direction D2, and the second capacitor C2 overlaps the other end of the one thermoelectric conversion portion 11 in the first direction D2. More specifically, in the thickness direction D1, the first capacitor C1 overlaps the second end 22b of the n-type thermoelectric conversion element 22 included in the one thermoelectric conversion portion 11, and the second capacitor C2 overlaps the second end 21b of the p-type thermoelectric conversion element 21 included in the one thermoelectric conversion portion 11.

[0055] The connection portion 7 is a conductive member electrically connected to both the thermoelectric conversion portion 11 and the heat conduction portion 5, and is located on the substrate 2. A portion of the connection portion 7 overlaps the heat conduction portion 5 or the heat insulating member 6 in the thickness direction D1, and is located between the substrate 2 and the heat conduction portion 5 or the heat insulating member 6. The connection portion 7 is, for example, a metal layer or an alloy layer formed by patterning on the substrate 2. Examples of metals contained in the connection portion 7 include Cu, Ni, and Au. The connection portion 7 is formed, for example, by plating. The thermal conductivity of the connection portion 7 is not particularly limited, but may be, for example, 3 W / mK or higher.

[0056] The connection portion 7 has a first portion 7a that contacts the substrate 2 and overlaps one end of each heat conductive portion 5 in the second direction D3, and a second portion 7b that contacts the substrate 2 and overlaps the other end of each heat conductive portion 5 in the second direction D3. In this embodiment, the first portion 7a contacts the external electrode 5c of each heat conductive portion 5, and the second portion 7b contacts the external electrode 5d of each heat conductive portion 5. Therefore, the heat conductive portions 5 (capacitors) are connected in parallel to each other via the first portion 7a and the second portion 7b.

[0057] FIG. 3B is a cross-sectional view taken along line IIIb-IIIb in FIG. 1A. As shown in FIG. 3B, a conductive material 8 is provided on the surface of the opening O1. The conductive material 8 is a conductive member that functions as a path electrically connecting the thermoelectric conversion unit 11 and the heat conduction unit 5, and covers the opening O1. The conductive material 8 is formed, for example, simultaneously with the connection unit 7. Therefore, the conductive material 8 is considered to be part of the first portion 7a of the connection unit 7. In this embodiment, the conductive material 8 is also formed on the first main surface 2a and in the vicinity of the opening O1, but this is not limited thereto. A conductive member connected to the conductive material 8 may be provided on the first main surface 2a. Although not shown, a conductive material that is considered to be part of the second portion 7b of the connection unit 7 is also provided on the surface of the opening O2.

[0058] The thermoelectric conversion module 1 may further include components other than those described above. For example, the thermoelectric conversion module 1 may include wiring for electrically connecting other thermoelectric conversion modules, wiring for extracting power to an external circuit, and the like.

[0059] In the thermoelectric conversion module 1 according to the present embodiment described above, the dielectric 5b exhibits heat resistance. Therefore, unlike when an aluminum electrolytic capacitor or the like is used, the capacitor does not need to be located away from the heat source. Furthermore, the substrate 2, the thermoelectric conversion unit 11, and the heat conduction unit 5, which is a capacitor electrically connected to the thermoelectric conversion unit 11, overlap each other in the thickness direction D1. This reduces the area occupied by the thermoelectric conversion module and the capacitor compared to a power supply in which the thermoelectric conversion module and the capacitor are simply arranged side by side. Additionally, the heat conduction unit 5 is arranged to exchange heat with the thermoelectric conversion unit 11 via the substrate 2. The thermal conductivity of the multiple internal electrodes 5a included in the heat conduction unit 5 and the thermal conductivity of the dielectric 5b are each 3 W / mK or greater. Therefore, even if a capacitor is located between the thermoelectric conversion unit 11 and the heat source in the thickness direction D1, the capacitor is not damaged, and heat can be transferred effectively from the heat source to the thermoelectric conversion unit 11 via the capacitor.

[0060] In this embodiment, the heat conducting portion 5 may be flexible. In this case, the thermoelectric conversion module 1 can be easily provided along the surface of a cylindrical pipe, for example. That is, restrictions on the location where the thermoelectric conversion module 1 can be attached can be alleviated.

[0061] In this embodiment, the thermoelectric conversion module 1 includes an insulating member 6 located on the second main surface 2b, and the thermoelectric conversion unit 11 has p-type thermoelectric conversion elements 21 and n-type thermoelectric conversion elements 22 arranged along the first direction D2, and the first end 21a of the p-type thermoelectric conversion element 21 in the first direction D2 is in contact with the first end 22a of the n-type thermoelectric conversion element 22 in the first direction D2 and overlaps the insulating member 6 in the thickness direction D1, and the multiple heat conduction units 5 are adjacent to each other along the first direction D2 via the insulating member 6 and have a first capacitor C1 and a second capacitor C2 in contact with the second main surface 2b, and the first capacitor C1 overlaps the second end 22b of the n-type thermoelectric conversion element 22 in the first direction D2 in the thickness direction D1, and the second capacitor C2 overlaps the second end 21b of the p-type thermoelectric conversion element 21 in the first direction D2 in the thickness direction D1. As a result, the first capacitor C1 and the second capacitor C2 each overlap the end of the thermoelectric conversion unit 11 in the thickness direction D1, but do not overlap the center of the thermoelectric conversion unit 11. Therefore, for example, by heating the first capacitor C1 and the second capacitor C2, an internal temperature difference can be effectively generated in each of the p-type thermoelectric conversion element 21 and the n-type thermoelectric conversion element 22.

[0062] In this embodiment, the thermoelectric conversion module 1 includes a connection portion 7 located on the second main surface 2b and electrically connected to both the thermoelectric conversion portion 11 and the heat conduction portion 5, which is a capacitor. This ensures good electrical connection between the thermoelectric conversion portion 11 and the capacitor.

[0063] Next, a thermoelectric conversion module according to a modified example will be described with reference to Figures 4 and 5. In the description of the modified example, descriptions that overlap with the above-described embodiment will be omitted, and only differences will be described. In other words, to the extent technically possible, the descriptions of the above-described embodiment may be used appropriately in the modified example.

[0064] Fig. 4A is a schematic bottom view showing a thermoelectric conversion module according to a first modified example. Fig. 4B is a cross-sectional view taken along line IVb-IVb in Fig. 4A. As shown in Figs. 4A and 4B, the thermoelectric conversion module 1A according to the first modified example differs from the thermoelectric conversion module 1 of the above embodiment in that a heat conduction unit 5A is provided instead of the heat conduction unit 5, which is a capacitor, and in that a capacitor C3 is further provided.

[0065] Each thermally conductive portion 5A exhibits a higher thermal conductivity than the substrate 2 and has a band-like shape in a planar view. The thermal conductivity of each thermally conductive portion 5A is, for example, 3 W / mK or more and 400 W / mK or less. This allows for efficient heat transfer to the thermoelectric conversion portion 11 via the multiple thermally conductive portions 5A when the thermoelectric conversion module 1 is heated. The thermal conductivity may be 5 W / mK or more, 8 W / mK or more, or 10 W / mK or more. The length T4 of each thermally conductive portion 5A along the thickness direction D1 is greater than the length T3 of the heat insulating member 6 and is, for example, 50 μm or more and 2000 μm or less. Each thermally conductive portion 5A includes, for example, a metal (silver, copper, etc.), carbon, or resin (e.g., silicone resin, epoxy resin, or (meth)acrylic resin). Each thermally conductive portion 5A may include a ceramic, such as boron nitride or aluminum nitride, that exhibits high thermal conductivity. In this embodiment, from the viewpoint of manufacturing efficiency, the thermally conductive portion 5A may include the above-mentioned resin. In this case, the heat conductive portion 5A may be formed using the resin or a solution containing the resin.

[0066] The capacitor C3 is flexible and capable of exchanging heat with the thermoelectric conversion unit 11 via the substrate 2 and at least one of the plurality of heat conductive units 5A. Therefore, the capacitor C3 can also function as a heat conductive unit. The capacitor C3 is a sheet capacitor that overlaps each heat conductive unit 5A and each heat insulating member 6 in the thickness direction D1 and is electrically connected to the thermoelectric conversion unit 11. The capacitor C3 is in contact with each heat conductive unit 5A and is spaced apart from the heat insulating member 6. Therefore, a space is provided between the capacitor C3 and the heat insulating member 6 in the thickness direction D1. In the first modification, the capacitor C3 is in close contact with the heat conductive unit 5A.

[0067] The length T5 of the capacitor C3 along the thickness direction D1 is, for example, 50 μm or more and 2000 μm or less. In a plan view, the capacitor C3 is located inside each edge of the substrate 2, but is not limited to this. The thermal conductivity of the capacitor C3 in the thickness direction D1 may be 3 W / mK or more, 5 W / mK or more, or even 10 W / mK or more. This allows for good heat transfer to the thermoelectric conversion unit 11 via the capacitor C3 and each heat conduction unit 5A when the thermoelectric conversion module 1A is heated. In addition, heat can be quickly dissipated from a portion of the thermoelectric conversion unit 11 via the capacitor C3 and each heat conduction unit 5A.

[0068] The capacitor C3 includes a plurality of first and second internal electrodes 51 and 52 stacked in the thickness direction D1, a dielectric 53, and a pair of external electrodes 54 and 55 electrically connected to the thermoelectric conversion unit 11. The functions and materials of the first and second internal electrodes 51 and 52 are similar to those of the first and second internal electrodes 5a1 and 5a2 included in the capacitor of the above embodiment. The functions and materials of the dielectric 53 are also similar to those of the dielectric 5b included in the capacitor of the above embodiment. In the first modification, in consideration of the flexibility of the capacitor C3, the dielectric 53 is made of a heat-resistant resin in which inorganic solid particles are dispersed. If the thermally conductive unit 5A includes a resin, the resin may be at least partially the same as the resin included in the dielectric 53. In this case, the resins are integrated to allow the capacitor C3 to adhere well to the thermally conductive unit 5A.

[0069] The functions, materials, etc. of the external electrodes 54, 55 are similar to those of the external electrodes 5c, 5d included in the capacitor of the above embodiment. The external electrode 54 contacts each first internal electrode 51 and is electrically connected to the first portion 7a of the connecting portion 7. The external electrode 55 contacts other electrodes included in each second internal electrode 52 and is electrically connected to the second portion 7b of the connecting portion 7. The external electrode 54 may be electrically connected to the first portion 7a via solder, a wire, or the like, or may be in direct contact with the first portion 7a. Similarly, the external electrode 55 may be electrically connected to the second portion 7b via solder, a wire, or the like, or may be in direct contact with the second portion 7b.

[0070] From the viewpoint of the heat conduction function of the capacitor C3, the thermal conductivity of the first internal electrode 51 and the second internal electrode 52, the thermal conductivity of the dielectric 53, and the thermal conductivity of the external electrodes 54, 55 may each be 3 W / mK or more. The thermal conductivity may be 5.0 W / mK or more, or 10.0 W / mK or more.

[0071] The thermoelectric conversion module 1A according to the first modified example described above also has the same effects as those of the above embodiment. In addition, by using the capacitor C3, the amount of electricity stored in the thermoelectric conversion module 1A can be increased.

[0072] 5 is a cross-sectional view of a main portion of a thermoelectric conversion module according to a second modification. As shown in FIG. 5, the thermoelectric conversion module 1B according to the second modification includes, in addition to the thermoelectric conversion module 1 of the above embodiment, a capacitor C3, which is the sheet capacitor shown in the first modification. The capacitor C3 overlaps the heat insulating member 6, the first capacitor C1, and the second capacitor C2 in the thickness direction D1, contacts the first capacitor C1 and the second capacitor C2, and is spaced apart from the heat insulating member 6. The capacitor C3 is electrically connected to the thermoelectric conversion unit 11, as in the first modification. Additionally, the capacitor C3 is connected in parallel with a plurality of heat conducting units 5, including the first capacitor C1 and the second capacitor C2.

[0073] In the thermoelectric conversion module 1B according to the second modified example described above, in addition to achieving the same effects as those of the above embodiment, the amount of electricity stored in the thermoelectric conversion module 1B can be further increased compared to the above first modified example.

[0074] The thermoelectric conversion module and the manufacturing method thereof according to the present disclosure are not limited to the above-described embodiment and modified examples, and various other modifications are possible.

[0075] In the above embodiment and modified example, the thermoelectric conversion elements are exposed on the first main surface, but this is not limited thereto. For example, the thermoelectric conversion elements may be covered with a sealing layer made of resin. Also, an insulator may be provided between two adjacent thermoelectric conversion groups. In this case, it is preferable that the thermal conductivity of the insulator be low in order to maintain the internal temperature difference of the thermoelectric conversion unit.

[0076] In the above embodiment and modified example, the heat insulating member is formed by drying the heat insulating material applied to the substrate, but this is not limiting. For example, a pre-formed heat insulating member may be fixed onto the substrate.

[0077] DESCRIPTION OF SYMBOLS 1, 1A, 1B... thermoelectric conversion module, 2... substrate, 2a... first main surface, 2b... second main surface, 3... thermoelectric conversion group, 4... conductive portion, 5, 5A... heat conductive portion, 5a... internal electrode, 5a1... first internal electrode, 5a2... second internal electrode, 5b... dielectric, 5c, 5d... external electrode, 6... heat insulating member, 7... connection portion, 7a... first portion, 7b... second portion, 8... conductive material, 11... thermoelectric conversion portion, 21... p-type thermoelectric conversion element, 21a... first end portion, 21b... second end portion, 22... n-type thermoelectric conversion element , 22a...first end, 22b...second end, 51...first internal electrode, 52...second internal electrode, 53...dielectric, 54, 55...external electrodes, C1...first capacitor (first thermal conductive portion), C2...second capacitor (second thermal conductive portion), C3...capacitor (sheet capacitor), D1...thickness direction, D2...first direction, D3...second direction, L1...length, L2...width, O1, O2...opening, R1...thermoelectric conversion region, R2...conductive region, S...spacing, T1...thickness, T2 to T5...length.

Claims

1. A thermoelectric conversion module comprising: a substrate having a first main surface and a second main surface located opposite the first main surface; a thermoelectric conversion unit located on the first main surface; and a capacitor located on the second main surface so as to be able to exchange heat with the thermoelectric conversion unit via the substrate and electrically connected to the thermoelectric conversion unit, wherein the substrate, the thermoelectric conversion unit, and the capacitor overlap one another in the thickness direction of the substrate, and the capacitor has a plurality of electrodes stacked on top of one another in the thickness direction, and a dielectric that fills gaps between the plurality of electrodes and exhibits heat resistance.

2. The thermoelectric conversion module according to claim 1, wherein the capacitor is flexible.

3. A thermoelectric conversion module as described in claim 1 or 2, further comprising an insulating member located on the second main surface, wherein the thermoelectric conversion unit has p-type thermoelectric conversion elements and n-type thermoelectric conversion elements aligned along a first direction perpendicular to the thickness direction, a first end of the p-type thermoelectric conversion element in the first direction contacts a first end of the n-type thermoelectric conversion element in the first direction and overlaps the insulating member in the thickness direction, the capacitors have a first capacitor and a second capacitor adjacent to each other along the first direction via the insulating member and in contact with the second main surface, wherein the first capacitor overlaps a second end of the n-type thermoelectric conversion element in the first direction in the thickness direction, and the second capacitor overlaps a second end of the p-type thermoelectric conversion element in the first direction in the thickness direction.

4. A thermoelectric conversion module as described in claim 3, wherein the capacitor further includes a sheet capacitor that overlaps the insulating member, the first capacitor, and the second capacitor in the thickness direction and is electrically connected to the thermoelectric conversion unit.

5. The thermoelectric conversion module according to claim 4, wherein the sheet capacitor is in contact with the first capacitor and the second capacitor and is spaced apart from the heat insulating member.

6. A thermoelectric conversion module as described in claim 1 or 2, further comprising: a heat insulating member located on the second main surface; and a first heat conducting portion and a second heat conducting portion adjacent to each other along a first direction perpendicular to the thickness direction via the heat insulating member, wherein the thermoelectric conversion portion has a p-type thermoelectric conversion element and an n-type thermoelectric conversion element aligned along the first direction, a first end of the p-type thermoelectric conversion element in the first direction contacts a first end of the n-type thermoelectric conversion element in the first direction and overlaps the heat insulating member in the thickness direction, the first heat conducting portion overlaps a second end of the n-type thermoelectric conversion element in the first direction in the thickness direction, and the second heat conducting portion overlaps a second end of the p-type thermoelectric conversion element in the first direction in the thickness direction, and the capacitor is capable of exchanging heat with the thermoelectric conversion portion via the substrate and at least one of the first heat conducting portion and the second heat conducting portion.

7. A thermoelectric conversion module as described in claim 6, wherein the capacitor is a sheet capacitor that overlaps the heat insulating member, the first heat conducting portion, and the second heat conducting portion in the thickness direction, and the sheet capacitor is in contact with the first heat conducting portion and the second heat conducting portion and is spaced apart from the heat insulating member.

8. The thermoelectric conversion module according to claim 1 or 2, further comprising a connection portion located on the substrate and electrically connected to both the thermoelectric conversion portion and the capacitor.

9. The thermoelectric conversion module according to claim 1 or 2, wherein the thermal conductivity of the plurality of electrodes and the thermal conductivity of the dielectric are each 3 W / mK or higher.

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