Stacked thermoelectric converter, thermoelectric conversion module, thermochemical battery, and thermoelectric sensor

Abstract

To provide a stacked thermoelectric converter, a thermoelectric conversion module, a thermochemical battery, and a thermoelectric sensor that can increase output voltage.SOLUTION: According to an embodiment of the present invention, there is provided a stacked thermoelectric converter 10 including three or more stacked electrodes 11A to 11C, and an electrolyte 12 interposed between the electrodes 11A and 11C and between the electrodes 11B and 11C, in contact with the electrodes 11A to 11C, and containing a redox couple.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a laminated thermoelectric conversion device, a thermoelectric conversion module, a thermochemical battery, and a thermoelectric sensor.

Background Art

[0002] In order to convert minute energy such as waste heat into electric power, the importance of thermoelectric conversion materials has been increasing. Among them, thermochemical batteries, which are thermoelectric conversion materials using a liquid as an electrolyte, have attracted attention because their performance has improved dramatically in recent years.

[0003] A thermochemical battery mainly comprises two electrodes and an electrolyte solution containing a redox pair interposed between the electrodes (see, for example, Patent Document 1), and generates electricity by applying a temperature difference between the electrodes. Here, when the distance between the electrodes of the thermochemical battery is large, the migration resistance of the ions constituting the redox pair increases. Therefore, in order to reduce the migration resistance of the ions, it is required that the distance between the electrodes be small.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in a single-cell thermochemical battery, simply reducing the distance between the electrodes causes a problem that the heat leak increases and it becomes difficult to apply a temperature difference between the electrodes, resulting in a decrease in the output voltage. For example, when the temperature of the heat source is 70°C and the outside air temperature is 25°C, in a thermochemical battery with a small distance between the electrodes, the temperature of the electrode on the heat source side becomes about 60°C and the temperature of the electrode on the outside air side becomes about 55°C, and sometimes a temperature difference of only about 5°C can be obtained.

[0006] The present invention has been made to solve the above problems. That is, an object of the present invention is to provide a laminated thermoelectric conversion device, a thermoelectric conversion module, a thermochemical battery, and a thermoelectric sensor capable of increasing an output voltage.

Means for Solving the Problems

[0007] [1] A laminated thermoelectric conversion device including three or more laminated electrodes, an electrolytic solution interposed between the electrodes, in contact with the electrodes, and containing a redox pair.

[0008] [2] The laminated thermoelectric conversion device according to [1] above, wherein the distance between adjacent electrodes is 2 mm or more and 30 mm or less, respectively.

[0009] [3] The laminated thermoelectric conversion device according to [1] or [2] above, further including a holding member that is interposed between the electrodes and holds the electrolytic solution so that the electrolytic solution is in contact with the electrodes.

[0010] [4] The laminated thermoelectric conversion device according to any one of [1] to [3] above, further including a gel interposed between the electrodes, the gel containing the electrolytic solution.

[0011] [5] A thermoelectric conversion module including two or more laminated thermoelectric conversion devices according to any one of [1] to [4] above, the two or more laminated thermoelectric conversion devices being connected in series.

[0012] [6] A thermoelectric conversion module including two or more laminated thermoelectric conversion devices according to any one of [1] to [4] above, the two or more laminated thermoelectric conversion devices being connected in parallel.

[0013] [7] A thermochemical battery including the laminated thermoelectric conversion device according to any one of [1] to [4] above or the thermoelectric conversion module according to [5] or [6] above, and a temperature difference applying mechanism for applying a temperature difference between the electrodes.

[0014] [8] The thermochemical battery according to [7] above, wherein the temperature difference applying mechanism includes a heating mechanism that heats one of the two outermost electrodes among the electrodes in the stacking direction of the electrodes.

[0015] [9] The thermochemical battery according to [7] above, wherein the temperature difference applying mechanism includes a cooling mechanism that cools one of the two outermost electrodes among the electrodes in the stacking direction of the electrodes.

[0016]

[10] A thermoelectric sensor comprising the laminated thermoelectric conversion device according to any one of [1] to [4] above or the thermoelectric conversion module according to [5] or [6] above.

Advantages of the Invention

[0017] According to the laminated thermoelectric conversion device, thermoelectric conversion module, thermochemical battery, and thermoelectric sensor according to the present invention, the output voltage can be increased.

Brief Description of the Drawings

[0018]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Embodiments for Carrying Out the Invention

[0019] Hereinafter, a laminated thermoelectric conversion device, a thermoelectric conversion module, a thermochemical battery, and a thermoelectric sensor according to an embodiment of the present invention will be described. FIG. 1 is a schematic plan view of the laminated thermoelectric conversion device according to the present embodiment, and FIG. 2 is a cross-sectional view taken along line A-A in FIG. 1. FIG. 3 is a schematic cross-sectional view of another laminated thermoelectric conversion device according to the present embodiment. FIG. 4 is a schematic configuration diagram of the thermoelectric conversion module according to the present embodiment, and FIG. 5 is a schematic configuration diagram of another thermoelectric conversion module according to the present embodiment. FIG. 6 is a schematic plan view of the thermochemical battery according to the present embodiment, and FIG. 7 is a cross-sectional view taken along line B-B in FIG. 6.

[0020] <<<Laminated Thermoelectric Conversion Device>>> As shown in FIGS. 1 and 2, the laminated thermoelectric conversion device 10 includes three laminated electrodes 11A, 11B, and 11C, and an electrolytic solution 12 that is interposed between the electrodes 11A and 11C and between the electrodes 11B and 11C, is in contact with the electrodes 11A, 11C and the electrodes 11B, 11C, and contains a redox pair. That is, the laminated thermoelectric conversion device 10 has a structure in which two cells sharing the electrode 11C, namely, a cell including the electrodes 11A and 11C and a cell including the electrodes 11B and 11C, are laminated. By adopting such a structure, the number of members such as electrodes can be reduced by one compared to the case where two single cells are laminated.

[0021] The laminated thermoelectric conversion device 10 further includes a frame-shaped sheet 14 disposed on the inner surfaces of electrodes 11A and 11B, and also disposed on the inner and outer surfaces of electrode 11C, a frame 15 interposed between electrodes 11A and 11C and between electrodes 11B and 11C, a holding member 16 for holding the electrolytic solution 12, a lid member 17 covering electrode 11B, and a bottom member 18 covering electrode 11A. Note that the laminated thermoelectric conversion device 10 may not include the frame-shaped sheet 14, the frame 15, the holding member 16, the lid member 17, and / or the bottom member 18.

[0022] <<Electrode>> The electrodes shown in FIG. 2 are composed of three electrodes 11A to 11C, but the number of electrodes is not particularly limited as long as it is three or more. For example, it may be four or more, six or more, or ten or more. Note that the upper limit of the number of electrodes may be twenty or less. If the number of electrodes is three or more (two cells or more), a temperature difference is likely to occur between the outermost electrodes, so the voltage can be increased compared to the case where the number of electrodes is two (single cell).

[0023] Electrodes 11A and 11B are the outermost electrodes among electrodes 11A to 11C in the stacking direction LD of electrodes 11A to 11C. Electrode 11C is located between electrodes 11A and 11B. That is, in the laminated thermoelectric conversion device 10, in the stacking direction LD, electrodes 11A, electrode 11C, and electrode 11B are arranged in this order.

[0024] Since the electrodes 11A to 11C shown in FIG. 2 are arranged in the order of electrode 11A, electrode 11C, and electrode 11B in the stacking direction LD of electrodes 11A to 11C, electrode 11A is adjacent to electrode 11C and electrode 11B is adjacent to electrode 11C. Electrode 11A has a take-out portion (not shown) for taking out a voltage, and electrode 11B has a take-out portion 11B1 for taking out a voltage as shown in FIG. 1.

[0025] In the laminated thermoelectric conversion device 10, when a temperature difference occurs between the electrode 11A and the electrode 11B, for example, when the electrode 11A becomes the high-temperature side electrode and the electrode 11B becomes the low-temperature side electrode, in the cell including the electrodes 11A and 11C, the electrode 11A becomes the negative electrode and the electrode 11C becomes the positive electrode, and in the cell including the electrodes 11B and 11C, the electrode 11C becomes the negative electrode and the electrode 11B becomes the positive electrode.

[0026] Examples of the material of the portions of the electrodes 11A to 11C that contact the electrolyte 12 include conductive materials such as platinum or carbon. Among these, platinum is preferable from the viewpoints of high dissolution potential and excellent corrosion resistance. Also, carbon is preferable from the viewpoints of low manufacturing cost and large surface area. The electrodes 11A to 11C may be formed by attaching carbon to a stainless steel plate, or may be flexible carbon plates.

[0027] The thickness of each of the electrodes 11A to 11C is preferably 0.02 mm or more and 3 mm or less. If this thickness is 0.02 mm or more, the shape can be sufficiently maintained even when the electrodes 11A to 11C are sandwiched between the like of the frame body 15, and if it is 3 mm or less, it is possible to suppress the temperature difference between the cells due to heat loss inside the electrodes 11A to 11C from becoming small. The lower limit of the thickness of each of the electrodes 11A to 11C is preferably 0.05 mm or more, 0.1 mm or more, or 0.5 mm or more, and the upper limit is preferably 2 mm or less, 1 mm or less, or 0.6 mm or less, respectively.

[0028] It is preferable that the distance D1 between the two outermost electrodes 11A and 11B in the stacking direction LD of the electrodes 11A to 11C is 5 mm or more. If this distance D1 is 5 mm or more, a sufficient temperature difference can be imparted between the electrodes 11A and 11C and between the electrodes 11B and 11C. The lower limit of this distance D1 is preferably 10 mm or more, 15 mm or more, or 20 mm or more. The upper limit of the distance D1 between the electrodes 11A and 11B is preferably 200 mm or less, 100 mm or less, or 50 mm or less from the viewpoint of maintaining the rigidity of the entire stacked thermoelectric conversion device 10. The distance D1 means the distance from the surface of the electrode 11A on the side of the electrode 11B to the surface of the electrode 11B on the side of the electrode 11A in the two outermost electrodes 11A and 11B in the stacking direction LD of the electrodes 11A to 11C.

[0029] In the electrodes 11A to 11C, the distance D2 between adjacent electrodes is preferably 2 mm or more and 30 mm or less, respectively. In the stacked thermoelectric conversion device 10, the distance D2 between the electrodes 11A and 11C and the distance D2 between the electrodes 11B and 11C are each 2 mm or more and 30 mm or less. If the distance D2 is 2 mm or more, a sufficient temperature difference can be imparted between the electrodes 11A and 11C and between the electrodes 11B and 11C, and if it is 30 mm or less, an increase in the migration resistance of the ions constituting the redox pair can be suppressed. The lower limit of this distance D2 may be 5 mm or more, 10 mm or more, or 20 mm or more, respectively, and the upper limit may be 20 mm or less, 10 mm or less, or 6 mm or less.

[0030] <<Electrolyte>> The electrolyte 12 contains a redox pair. Further, the electrolyte 12 further contains a solvent. The electrolyte 12 may be contained in the gel interposed between the electrodes 11A and 11C and between the electrodes 11B and 11C. The pH of the electrolyte is preferably 2 or more and 11 or less from the viewpoint of preventing corrosion of metal parts such as lead wires attached to the electrodes 11A and the like.

[0031] <Redox pair> A redox pair consists of an oxidizing agent active species and a reducing agent active species. It can be reduced from the oxidizing agent active species to the reducing agent active species by a reduction reaction, or oxidized from the reducing agent active species to the oxidizing agent active species by an oxidation reaction. The redox pair is preferably one pair selected from the group consisting of iodide ion and triiodide ion, ferrocyanide ion and ferricyanide ion, cobalt trisbipyridine (II) and cobalt trisbipyridine (III), ferrocenemonocarboxylic acid (FeII) and ferricenium monocarboxylic acid (FeIII), oxoaquavanadium (IV) complex and oxoaquavanadium (V) complex. Among these, from the viewpoint of a large electromotive force per unit temperature difference and stability against water and air, a pair consisting of ferrocyanide ion and ferricyanide ion is preferable.

[0032] <Solvent> The solvent is preferably an aqueous solvent containing water and an organic solvent or water. The acidic aqueous solvent is not particularly limited, and examples thereof include sulfuric acid aqueous solution, phosphoric acid aqueous solution, citric acid aqueous solution, or hydrochloric acid aqueous solution. Among these, from the viewpoint of the buffering action in the above pH range, it is preferable to use a sulfuric acid aqueous solution.

[0033] <<Frame-shaped sheet>> The frame-shaped sheet 14 has an opening 14A. The opening area of the opening 14A is smaller than the areas of the electrodes 11A to 11C. By disposing the frame-shaped sheet 14 on the inner surfaces of the electrodes 11A and 11B, and on the inner and outer surfaces of the electrode 11C, it is possible to suppress the leakage of the solvent from the gap between the frame 15 and the electrodes 11A to 11C.

[0034] The frame-shaped sheet 14 is made of an electrically insulating material. Examples of the electrically insulating material include silicone resin, rubbers such as styrene-butadiene rubber and acrylonitrile rubber, fluororesins such as polytetrafluoroethylene and polyvinylidene fluoride, and polyolefin resins such as polypropylene and polyethylene.

[0035] The thickness of the frame-shaped sheet 14 is preferably 0.1 mm or more and 3 mm or less, respectively. If the thickness of the frame-shaped sheet 14 is 0.1 mm or more, the leakage of the solvent can be sufficiently prevented, and if it is 3 mm or less, the thickness of the entire laminated thermoelectric conversion device 10 can be minimized. The lower limit of the thickness of the frame-shaped sheet 14 may be 0.2 mm or more, 0.5 mm or more, or 1 mm or more, respectively, and the upper limit may be 2 mm or less, 1 mm or less, or 0.8 mm or less, respectively.

[0036] <<Frame body>> The frame body 15 has an opening 15A. The opening area of the opening 15A is smaller than the areas of the electrodes 11A to 11C. In the laminated thermoelectric conversion device 10 shown in FIG. 2, the opening area of the opening 15A of the frame body 15 is the same as the opening area of the opening 14A of the frame-shaped sheet 14. The inside of the opening 15A of the frame body 15 is filled with the electrolytic solution 12. In the laminated thermoelectric conversion device 10, the thicknesses of the frame body 15 disposed between the electrodes 11A and 11C and between the electrodes 11B and 11C are preferably in the same range as the distance D2, respectively. The frame body 15 is made of an electrically insulating material. The electrically insulating material is not particularly limited, and examples thereof include resins.

[0037] <<Holding member>> The holding member 16 is for holding the electrolytic solution 12 so that the electrolytic solution 12 contacts the electrodes 11A to 11C. By holding the electrolytic solution 12 in the holding member 16, leakage of the electrolytic solution 12 from the frame body 15 can be suppressed. The holding member 16 is not particularly limited as long as it can hold the electrolytic solution 12 so that the electrolytic solution 12 contacts the electrodes 11A to 11C, and examples thereof include liquid-absorbing members such as sponges. In the laminated thermoelectric conversion device 10, the thicknesses of the holding member 16 located between the electrodes 11A and 11C and between the electrodes 11B and 11C are preferably in the same range as the distance D2, respectively.

[0038] In the laminated thermoelectric conversion device 10, when a temperature difference occurs between the two outermost electrodes 11A and 11B in the lamination direction LD of the electrodes 11A to 11C, a temperature distribution occurs between the electrodes 11A and 11B. In the cells including the electrodes 11A and 11C and the cells including the electrodes 11B and 11C, a reduction reaction occurs at the low-temperature side electrode and an oxidation reaction occurs at the high-temperature side electrode, respectively. As a result, a potential difference occurs due to the temperature difference between the low-temperature side electrode and the high-temperature side electrode, and an electromotive force is generated between the low-temperature side electrode and the high-temperature side electrode.

[0039] The temperature difference between the electrodes 11A and 11B is preferably 5°C or more, although it depends on the application of the thermoelectric conversion device. If the temperature difference between the electrodes 11A and 11B is 5°C or more, the temperature difference is sufficient, so the output voltage can be increased. The lower limit of the temperature difference between the electrodes 11A and 11B is more preferably 10°C or more, 20°C or more, or 30°C or more, and the upper limit may be 100°C or less.

[0040] The temperature differences between the electrodes 11A and 11C and between the electrodes 11B and 11C are preferably 1°C or more, although they depend on the application of the thermoelectric conversion device. If the temperature differences between the electrodes 11A and 11C and between the electrodes 11B and 11C are 1°C or more, respectively, the temperature differences are sufficient, so the output voltage can be increased. The lower limits of the temperature differences between the electrodes 11A and 11C and between the electrodes 11B and 11C are more preferably 5°C or more, 10°C or more, or 15°C or more, and the upper limits may be 20°C or less.

[0041] <<<Other laminated thermoelectric conversion devices>>> The laminated thermoelectric conversion device 10 shown in FIG. 2 includes three laminated electrodes, while the laminated thermoelectric conversion device 20 shown in FIG. 3 includes four laminated electrodes. The laminated thermoelectric conversion device 20 includes at least four laminated electrodes 11A, 11B, 11C, 11D, and an electrolytic solution 12 that is interposed between electrodes 11A and 11C, between electrodes 11C and 11D, and between electrodes 11B and 11D, is in contact with electrodes 11A, 11C, electrodes 11C, 11D, and electrodes 11B, 11D, and contains a redox pair. That is, in the laminated thermoelectric conversion device 20, in the cells including electrodes 11A and 11C and the cells including electrodes 11C and 11D, electrode 11C is shared, and in the cells including electrodes 11C and 11D and the cells including electrodes 11B and 11D, electrode 11D is shared, and three cells are laminated. By adopting such a structure, the number of members such as electrodes can be reduced by two compared to the structure in which three single cells are laminated. Note that among the members shown in FIG. 3, the members with the same reference numerals as those in FIG. 2 are the same as the members shown in FIG. 2.

[0042] In the laminated thermoelectric conversion device 20, in addition to electrodes 11A to 11C, electrode 11D is provided. Since electrode 11D is located between electrodes 11B and 11C, in the lamination direction LD of electrodes 11A to 11D, electrodes 11A, 11C, 11D, and 11B are arranged in this order.

[0043] Since electrodes 11A to 11D are arranged in the order of electrodes 11A, 11C, 11D, and 11B in the lamination direction LD of electrodes 11A to 11D, electrode 11A is adjacent to electrode 11C, electrode 11C is adjacent to electrode 11D, and electrode 11B is adjacent to electrode 11D.

[0044] In the laminated thermoelectric conversion device 20, for example, when the electrode 11A becomes the high-temperature side electrode and the electrode 11B becomes the low-temperature side electrode, in the cell including the electrodes 11A and 11C, the electrode 11A becomes the negative electrode and the electrode 11C becomes the positive electrode. In the cell including the electrodes 11C and 11D, the electrode 11C becomes the negative electrode and the electrode 11D becomes the positive electrode. In the cell including the electrodes 11B and 11D, the electrode 11D becomes the negative electrode and the electrode 11B becomes the positive electrode.

[0045] The thicknesses of the electrodes 11A to 11D and the distances D1 and D2 of the laminated thermoelectric conversion device 20 are the same as those of the electrodes 11A to 11C and the distances D1 and D2 of the laminated thermoelectric conversion device 10, respectively, and thus the description thereof will be omitted.

[0046] In the laminated thermoelectric conversion device 20, when a temperature difference occurs between the two outermost electrodes 11A and 11B in the stacking direction LD of the electrodes 11A to 11D, in the cell including the electrodes 11A and 11C, the cell including the electrodes 11C and 11D, and the electrodes 11B and 11D, a reduction reaction occurs at the low-temperature side electrode and an oxidation reaction occurs at the high-temperature side electrode, respectively. As a result, a potential difference is generated due to the temperature difference between the low-temperature side electrode and the high-temperature side electrode, and an electromotive force is generated between the low-temperature side electrode and the high-temperature side electrode.

[0047] The temperature difference between the electrodes 11A and 11B in the laminated thermoelectric conversion device 20 and the temperature differences between the electrodes 11A and 11C, between the electrodes 11C and 11D, and between the electrodes 11B and 11D are also the same as those of the laminated thermoelectric conversion device 10.

[0048] According to the present embodiment, in the stacked thermoelectric conversion device 10, since three electrodes 11A to 11C are stacked, the distance D1 between the two outermost electrodes 11A and 11B in the stacking direction LD of the electrodes 11A to 11C can be increased, and the distance D2 between the adjacent electrodes 11A and 11C and the distance D2 between the electrodes 11B and 11C can be decreased. As a result, when a temperature difference is applied to or occurs between the electrodes 11A and 11B, since the distance D1 between the electrodes 11A and 11B is large, heat leakage can be suppressed, and a sufficient temperature difference can be generated between each of the electrodes 11A and 11C and the electrodes 11B and 11C. Further, since the distance D2 between the electrodes 11A and 11C and the distance D2 between the electrodes 11B and 11C are small, the movement resistance of the ions constituting the redox pair can be decreased. Thereby, the output voltage can be increased. Also in the stacked thermoelectric conversion device 20, for the same reason as the stacked thermoelectric conversion device 10, the output voltage can be increased. In the above description, the case where the thermoelectric conversion device stacks three or four electrodes has been described, but if there are three or more electrodes, the above effects can be obtained.

[0049] <<Thermoelectric Conversion Module>> The stacked thermoelectric conversion devices 10 and 20 may be used by connecting two or more stacked thermoelectric conversion devices 10 and 20 in series or in parallel. The thermoelectric conversion module 30 shown in FIG. 4 is obtained by electrically connecting two stacked thermoelectric conversion devices 10 in series. Since the two stacked thermoelectric conversion devices 10 are electrically connected in series in the thermoelectric conversion module 30, the voltage can be increased compared to one stacked thermoelectric conversion device 10. In the thermoelectric conversion module 30 shown in FIG. 4, although two stacked thermoelectric conversion devices 10 are electrically connected in series, three or more stacked thermoelectric conversion devices 10 may be electrically connected in series. Further, the thermoelectric conversion module 30 may be obtained by electrically connecting two or more stacked thermoelectric conversion devices 20 in series instead of the stacked thermoelectric conversion device 10.

[0050] The thermoelectric conversion module 40 shown in FIG. 5 is formed by electrically connecting two stacked thermoelectric conversion devices 10 in parallel. Since the two stacked thermoelectric conversion devices 10 of the thermoelectric conversion module 40 are electrically connected in parallel, the current can be increased compared to a single stacked thermoelectric conversion device 10. In the thermoelectric conversion module 40 shown in FIG. 5, although two stacked thermoelectric conversion devices 10 are electrically connected in parallel, three or more stacked thermoelectric conversion devices 10 may be electrically connected in parallel. Further, the thermoelectric conversion module 40 may be formed by electrically connecting two or more stacked thermoelectric conversion devices 20 in parallel instead of the stacked thermoelectric conversion device 10.

[0051] <<Thermochemical battery>> As shown in FIGS. 6 and 7, the thermochemical battery 50 includes a stacked thermoelectric conversion device 10 and a temperature difference applying mechanism 51 that applies a temperature difference to the electrodes 11A and 11B. Note that the thermochemical battery may include a stacked thermoelectric conversion device 20 or a thermoelectric conversion module 30 or 40 instead of the stacked thermoelectric conversion device 10.

[0052] <Temperature difference applying mechanism> The temperature difference applying mechanism 51 is for applying a temperature difference between the electrodes 11A and 11C and between the electrodes 11B and 11C. The temperature difference applying mechanism 51 includes a heating mechanism 52 and a cooling mechanism 53. The temperature difference applying mechanism 51 may include the heating mechanism 52 without including the cooling mechanism 53, or may include the cooling mechanism 53 without including the heating mechanism 52.

[0053] The heating mechanism 52 heats one of the two outermost electrodes 11A and 11B among the electrodes 11A to 11C. In FIG. 7, the heating mechanism 52 is in contact with the electrode 11A and heats the electrode 11A. The heating mechanism 52 is not particularly limited as long as it can heat the electrode 11A, but it is preferably a heating mechanism that utilizes waste heat. By the heating mechanism 52 utilizing waste heat, the waste heat can be effectively utilized. The heating mechanism 52 is preferably, for example, a heating mechanism that uses a gas having waste heat. The heating mechanism 52 includes a heating member 52A having a flow path 52A1, a gas supply system (not shown) connected to the flow path inlet of the heating member 52A, and a gas discharge system (not shown) connected to the flow path outlet of the heating member 52A. By supplying a gas having waste heat from the gas supply system to the heating member 52A, the gas having waste heat flows through the flow path 52A1 of the heating member 52A, so that the electrode 11A can be heated.

[0054] The heating mechanism 52 preferably heats the electrode 11A so that the temperature of the electrode 11A becomes 30°C or higher. If the temperature of the electrode 11A is 30°C or higher, a temperature difference can be effectively applied between the electrode 11A and the electrode 11C and between the electrode 11B and the electrode 11C, respectively. The lower limit of the temperature of the electrode 11A is preferably 35°C or higher, 40°C or higher, or 50°C or higher. The upper limit of the temperature of the electrode 11A may be 200°C or lower from the viewpoint of utilization of industrial waste heat.

[0055] The cooling mechanism 53 heats the other one of the two outermost electrodes 11A and 11B among the electrodes 11A to 11C. In FIG. 7, the cooling mechanism 53 is in contact with the electrode 11B and cools the electrode 11B. The cooling mechanism 53 is not particularly limited as long as it can cool the electrode 11B. For example, it is preferably a cooling mechanism using a cooling medium. The cooling mechanism 53 includes a cooling member 53A having a flow path 53A1, a cooling medium supply system 53B connected to the flow path inlet of the cooling member 53A, and a cooling medium discharge system 53C connected to the flow path outlet of the cooling member 53A. By supplying the cooling medium from the cooling medium supply system 53B to the cooling member 53A, the cooling medium flows in the flow path 53A1 of the cooling member 53A, so that the electrode 11B can be cooled.

[0056] The cooling mechanism 53 preferably cools the electrode 11B so that the temperature of the electrode 11B becomes 25°C or lower. If the temperature of the electrode 11B is 25°C or lower, a temperature difference can be effectively applied between the electrode 11A and the electrode 11C and between the electrode 11B and the electrode 11C, respectively. The upper limit of the temperature of the electrode 11B may be 30°C or lower, 35°C or lower, or 40°C or lower. The lower limit of the temperature of the electrode 11B may be 0°C or higher. The cooling solvent is not particularly limited, and examples thereof include water.

[0057] <<Thermoelectric sensor>> The thermoelectric sensor is a device that utilizes the above-described laminated thermoelectric conversion devices 10 and 20 or the above-described thermoelectric conversion modules 30 and 40 to sense the temperature difference between electrodes 11A and 11B. Since the laminated thermoelectric conversion devices 10 and 20 or the above-described thermoelectric conversion modules 30 and 40 have a high output voltage, they have high sensitivity as a temperature sensor. For example, when a laminated thermoelectric conversion device is used as a thermoelectric sensor, a voltage of 2 mV can be generated even with a temperature difference of 1 °C between the electrodes. By connecting a device for measuring a potential difference, such as a precise voltmeter, a sensor capable of recognizing a difference of about 0.000001 °C can be created. If such a small temperature difference can be recognized, for example, heat transmitted from the body temperature of a person on the other side of the wall heats one of the electrodes, and the person can be sensed. Also, weak infrared rays radiated from a heat source can be sensed. Further, when a material that can absorb specific light such as ultraviolet light and generate heat is provided on one electrode side, it can be applied to a thermoelectric sensor that senses a small amount of light.

Example

[0058] To explain the present invention in detail, examples will be given below for explanation, but the present invention is not limited to these descriptions. FIG. 8 is a graph showing the relationship between the closed-circuit voltage and the temperature difference of the thermochemical cells according to Example 1, Example 2, and Comparative Example 1. FIG. 9 is a graph showing the power-voltage relationship of the thermochemical cells according to Example 1, Example 2, and Comparative Example 1. FIG. 10 is a graph showing the electrode temperatures on the high-temperature side and the low-temperature side when the temperature of the heating-side Peltier element of the thermochemical cells according to Example 1, Example 2, and Comparative Example 1 is fixed at 50 °C. FIG. 11 is a graph showing the electrode temperatures on the high-temperature side and the low-temperature side when the temperature of the heating-side Peltier element of the thermochemical cells according to Example 1, Example 2, and Comparative Example 1 is fixed at 70 °C.

[0059] <Examples 1 and 2 and Comparative Example 1> First, K3[Fe(CN)6] and K4[Fe(CN)6] were prepared, and K3[Fe(CN)6] and K4[Fe(CN)6] were dissolved in water to obtain an electrolytic solution with a pH of 7 containing 3- / 4- (400 mM each) of [Fe(CN)6].

[0060] An electrode made of a carbon sheet with a thickness of 1 mm and a size of 6 cm × 6 cm, a frame-shaped sheet made of a silicone rubber sheet with a thickness of 1 mm, and a resin frame made of 2-hydroxypropyl polymethacrylate were prepared. The frame-shaped sheet and the frame were each cut out in a square shape with a side length of 2.5 cm at the center. Also, three types of frames with thicknesses of 1 cm, 1.5 cm, and 3 cm were prepared.

[0061] After preparing these, using the above electrode, the above frame-shaped sheet, and the frame with a thickness of 1 cm, they were laminated in the order of electrode, frame-shaped sheet, frame, frame-shaped sheet, electrode, frame-shaped sheet, frame, frame-shaped sheet, electrode, and at the same time, the above-prepared [Fe(CN)6] was placed in the spaces separated by the electrodes respectively. 3- / 4- and the resulting electrolyte was injected. Also, Peltier elements were respectively arranged on the two outermost electrodes as a temperature difference applying mechanism (heating mechanism and cooling mechanism). In the following measurement tests, the output of each Peltier element was electronically controlled so that the temperature of each Peltier element became constant. As a result, a thermochemical battery according to Example 1 having three laminated electrodes (two cells), an electrode spacing of about 1 cm, and a thickness of about 3 cm was fabricated.

[0062] Also, using the above electrode, the above frame-shaped sheet, and the frame with a thickness of 1.5 cm, they were laminated in the order of electrode, frame-shaped sheet, frame, frame-shaped sheet, electrode, frame-shaped sheet, frame, frame-shaped sheet, electrode, frame-shaped sheet, frame, frame-shaped sheet, electrode, and at the same time, the above-prepared [Fe(CN)6] was placed in the spaces separated by the electrodes respectively. 3- / 4- and the resulting electrolyte was injected. Also, Peltier elements were respectively arranged on the two outermost electrodes. As a result, a thermochemical battery according to Example 2 having four laminated electrodes (three cells), an electrode spacing of about 1.5 cm, and a thickness of about 3 cm was fabricated.

[0063] Furthermore, using the above electrode, the above frame-shaped sheet, and the frame with a thickness of 3 cm, they were laminated in the order of electrode, frame-shaped sheet, frame, frame-shaped sheet, electrode, and at the same time, the above-prepared [Fe(CN)6] was placed in the spaces separated by the electrodes. 3- / 4- An electrolytic solution consisting of [the relevant components] was injected. Also, Peltier elements were respectively arranged on the two electrodes. Thereby, a thermochemical battery according to Comparative Example 1 having two laminated electrodes (one cell), with an inter-electrode distance of about 3 cm and a thickness of about 3 cm, was fabricated.

[0064] <Measurement Test> In the thermochemical batteries according to Example 1, Example 2, and Comparative Example 1, using Peltier elements, the open-circuit voltage (ΔV) generated between the electrodes of the thermochemical battery was monitored for various ΔT. Then, the measurement results were shown in a graph of ΔV versus ΔT, and from the slope, the Seebeck coefficient (S e ) which is the voltage per unit temperature was obtained. As shown in Figure 8, the S e value of the thermochemical battery was -1.37 mV / K in Example 1, -1.39 mV / K in Example 2, and -1.27 mV / K in Comparative Example 1. The reason why the S e value of the thermochemical battery according to Comparative Example 1 was estimated to be about 0.1 mV / K smaller than those of the thermochemical batteries according to Example 1 and Example 2 is presumably because the thickness of the frame of the thermochemical battery according to Comparative Example 1 was large, the influence of the convection of the electrolytic solution became large, and the effective temperature of the electrode surface became smaller than the measured value. Anyway, the S e values evaluated from the above three thermochemical batteries are in good agreement within a difference of within 10%, indicating that the S e value depends only on the redox pair and does not depend on the number of laminations.

[0065] In the thermochemical batteries according to Example 1, Example 2, and Comparative Example 1, with the temperature of the Peltier element fixed at 20 °C on the cooling side and 70 °C on the heating side, the power with respect to the voltage was measured. As shown in Figure 9, in the thermochemical battery according to Example 1, the open-circuit voltage was -45 mV and the maximum power was 12.5 μW / cm 2 , in the thermochemical battery according to Example 2, the open-circuit voltage was -40 mV and the maximum power was 11.8 μW / cm 2 , and in the thermochemical battery according to Comparative Example 1, the open-circuit voltage was -31 mV and the maximum power was 9.5 μW / cm 2It was. From this result, it was confirmed that the voltage and power increased significantly as the number of cell layers increased.

[0066] In the thermochemical batteries according to Example 1, Example 2, and Comparative Example 1, with the temperature of the Peltier element set at 20°C on the cooling side and 50°C or 70°C on the heating side, two thermistors were inserted between the frame-shaped sheet and the outermost electrode, respectively, and the temperature near the inner surface of the outermost electrode was measured, and the measured temperature was taken as the temperature of the outermost electrode. As shown in FIG. 10, under the condition that the temperature of the Peltier element on the heating side was fixed at 50°C, the temperature difference between the outermost electrodes of the thermochemical battery was 21.3°C in Example 1, 18.0°C in Example 2, and 15.8°C in Comparative Example 1. The larger the number of cells stacked, the larger the temperature difference between the outermost electrodes. Furthermore, as shown in FIG. 11, under the condition that the temperature of the Peltier element on the heating side was fixed at 70°C, the temperature difference between the outermost electrodes of the thermochemical battery was 33.4°C in Example 1, 29.0°C in Example 2, and 22.6°C in Comparative Example 1. Also in this case, the larger the number of cells stacked, the more the temperature difference between the outermost electrodes tended to increase. From this result, when comparing thermochemical batteries with the same total thickness of the frame, it was shown that by designing the frame to be thinner and increasing the number of cell layers, the temperature difference between the outermost electrodes becomes larger. The reason for this is that the smaller the thickness of the frame, the more the convection of the electrolyte between the electrodes is suppressed, and the larger the number of cell layers, the more the thermal conductivity of the entire thermochemical battery is suppressed.

Explanation of Symbols

[0067] 10, 20... Stacked thermoelectric conversion device 11A, 11B, 11C, 11D... Electrodes 12... Electrolyte 15... Frame 16... Holding member 30, 40... Thermoelectric conversion module 50... Stacked thermochemical battery 51... Temperature difference applying mechanism 52... Heating mechanism 53... Cooling mechanism

Claims

1. Three or more stacked electrodes, An electrolytic solution interposed between each of the electrodes, in contact with the electrodes, and containing a redox pair, A stacked thermoelectric conversion device comprising the same.

2. The stacked thermoelectric conversion device according to Claim 1, wherein the distance between adjacent electrodes is each 2 mm or more and 30 mm or less.

3. The stacked thermoelectric conversion device according to Claim 1, further comprising a holding member that is interposed between each of the electrodes and holds the electrolytic solution so that the electrolytic solution is in contact with the electrodes.

4. The stacked thermoelectric conversion device according to Claim 1, further comprising a gel interposed between each of the electrodes, the gel containing the electrolytic solution.

5. A thermoelectric conversion module comprising two or more stacked thermoelectric conversion devices according to Claim 1, wherein two or more of the stacked thermoelectric conversion devices are connected in series.

6. A thermoelectric conversion module comprising two or more stacked thermoelectric conversion devices according to Claim 1, wherein two or more of the stacked thermoelectric conversion devices are connected in parallel.

7. A thermochemical battery comprising the stacked thermoelectric conversion device according to Claim 1 or the thermoelectric conversion module according to Claim 5 or Claim 6, And a temperature difference applying mechanism for applying a temperature difference between each of the electrodes.

8. The thermochemical battery according to Claim 7, wherein the temperature difference applying mechanism includes a heating mechanism for heating one of the two outermost electrodes among the electrodes in the stacking direction of the electrodes.

9. The thermochemical battery according to Claim 7, wherein the temperature difference applying mechanism includes a cooling mechanism for cooling one of the two outermost electrodes among the electrodes in the stacking direction of the electrodes.

10. A thermoelectric sensor comprising the stacked thermoelectric conversion device according to Claim 1 or the thermoelectric conversion module according to Claim 5 or Claim 6.

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