TWI739759B - Thermoelectric element and thermoelectric module comprising the same, and method of thermoelectric generation using the same - Google Patents

Abstract

The object of the present invention is to provide a thermoelectric element that requires no temperature gradient and a thermoelectric generation system using the same. The object of the present invention is solved by a thermoelectric element characterized in that a first layer comprising a thermoelectric material which produces thermally excited electrons and holes, and a second layer comprising a solid electrolyte or an electrolyte solution in which an ion pair for charge transport can move are laminated; a valance band potential of the thermoelectric material which produces thermally excited electrons and holes in the first layer is more positive with respect to an oxidation-reduction potential of the ion pair for charge transport; and an ion which is susceptible to oxidation among the two ions is oxidized at an interface between the first layer and the second layer.

Description

Thermoelectric power generation element, thermoelectric power generation module containing it, and thermoelectric power generation method using it

The present invention relates to a thermoelectric power generation element, a thermoelectric power generation module containing it, and a thermoelectric power generation method using it. According to the present invention, it is possible to convert thermal energy into electrical energy without imparting a temperature gradient to the thermoelectric power generation element.

Conventionally, as thermoelectric power generation using geothermal energy or factory exhaust heat, thermoelectric power generation systems using the Seebeck effect have been known (Patent Documents 1, 2 and Non-Patent Document 1), because thermal energy is used efficiently, Its practicality is expected. Thermoelectric power generation based on the Seebeck effect uses the power generation principle that voltage is generated when a temperature gradient is placed on a metal or semiconductor. Specifically, it is a thermoelectric power generation system that converts thermal energy into electrical energy by imparting a temperature gradient to a thermoelectric conversion element that combines a p-type semiconductor and an n-type semiconductor.

This thermoelectric power generation system does not generate greenhouse effect gases that are emitted by thermal power generation. In addition, in areas with many volcanoes, you can put Geothermal heat is used as thermal energy, so it is a promising method of power generation.

[Prior technical literature] 〔Patent Documents〕

[Patent Document 1] JP 2010-147236 A

[Patent Document 2] JP 2003-219669 A

〔Non-patent literature〕

[Non-Patent Document 1] "Renewable and Sustainable Energy Reviews" (Netherlands) 2014, Vol. 33, p.371

[Non-Patent Document 2] "Photoelectric Series 3 Solar Cells" edited by Keihiro Hamagawa, published by Corona, 2004

However, conventional thermoelectric conversion elements using temperature gradients have problems such as high price of semiconductors constituting the thermoelectric conversion elements, narrow operating temperature range, and low conversion efficiency. Furthermore, because power generation requires a temperature gradient, the set of field restrictions may require the use of cooling devices for generating temperature gradients depending on the location. Especially in the thermoelectric conversion module, the primary element is used for the temperature gradient, and the heat source becomes the use of the secondary element. It is impossible to use all the surrounding heat in three dimensions, so there is a disadvantage of low heat utilization efficiency.

In other words, the object of the present invention is to provide a thermoelectric power generation element that does not require a temperature gradient and a thermoelectric power generation system using the same.

The inventor of the present case, after intensive research on thermoelectric conversion elements that do not require temperature gradients and the thermoelectric power generation system using them, was surprised to find that the combination of thermoelectric conversion materials that generate thermally excited electrons and positive pores, and The charge transport ion pair can move the thermoelectric conversion element of solid electrolyte or electrolyte solution. Even if the temperature difference is not provided to the system, as long as the whole system is placed at a high temperature, the heat energy can be converted into electric energy.

The present invention is an invention completed based on such knowledge.

That is, the present invention relates to

[1] The first layer is characterized in that it contains a thermoelectric conversion material that generates thermally excited electrons and positive pores, and a second layer that contains a solid electrolyte or an electrolyte solution in which charge transport ion pairs can move is laminated, and the inside of the first layer The valence electron charge potential of the semiconductor that generates thermally excited electrons and positive pores is more positive than the redox potential of the aforementioned charge transport ion pair in the second layer. At the interface between the first layer and the second layer, the aforementioned 2 A thermoelectric generating element for the oxidation reaction of the more easily oxidized ions among the ions

[2] The thermoelectric power generation element according to [1], wherein the valence electron charge potential of the thermoelectric conversion material that generates thermally excited electrons and positive pores in the first layer and the oxidation-reduction of the charge transport ion pair in the second layer The potential difference is below 0.5V

[3] The thermoelectric power generation element such as [1] or [2], which contains electron transport materials The third layer of the material is laminated on the side opposite to the laminated surface of the second layer of the first layer. The electron conduction band potential of the electron transport material in the third layer is the same as that in the first layer. The conduction band potential of the thermoelectric conversion material of the thermally excited electron and the positive hole is the same or positive

[4] The thermoelectric power generation element of [3], wherein the conduction band potential of the thermoelectric conversion material that generates thermionic and positive pores in the first layer and the electron conduction band potential of the electron transport material in the third layer are different The difference is below 0.5V

[5] The thermoelectric power generation element of any one of [1] to [4], wherein the thermoelectric conversion material in the first layer that generates thermally excited electrons and positive holes is the thermally excited electrons and the positive electricity generated with them Thermoelectric conversion material with a hole potential difference of 0.1V or more

[6] A method of generating electricity, in which the thermoelectric generating element of any one of [1] to [5] is placed so as to generate the thermally excited electron density of the thermoelectric conversion material that generates the thermally excited electrons and positive pores in the first layer Power generation in an environment with a temperature of 10 ¹⁵ /m ^{3 or higher}

[7] The power generation method as in [6], wherein the aforementioned temperature is the temperature at which the thermally excited electron density of the thermoelectric conversion material becomes 10 ¹⁸ /m ³

[8] A thermoelectric power generation device including any thermoelectric power generation element from [1] to [5]

[9] A thermal battery, including any one of [1] ~ [5] thermoelectric power generation element

[10] A thermoelectric power generation module including any thermoelectric power generation element from [1] to [5]

[11] A method of thermoelectric power generation, comprising: installing the thermoelectric power generation module of [10] in a place where heat is generated, and heating the thermoelectric power generation module by heat to generate electricity, and [12] Such as [11] in the thermoelectric power generation method, wherein the aforementioned heat is geothermal or exhaust heat.

In addition, this manual also reveals

[13] A thermoelectric conversion layer containing (1) a thermoelectric conversion material that generates positive electricity pores and electrons, and (2) an electron transport layer containing an electron transport material and/or a positive electricity pore transport layer of a positive electricity transport material Thermoelectric power generation element

[14] Thermoelectric power generation device containing the aforementioned thermoelectric power generation element

[15] Thermal battery containing the aforementioned thermoelectric power generation element

[16] A thermoelectric power generation module including the above-mentioned thermoelectric power generation element, and [17] includes the steps of: installing the above-mentioned thermoelectric power generation module in a place where heat is generated, and heating the above-mentioned thermoelectric power generation module by the heat to generate electricity The steps of the thermoelectric power generation method.

According to the thermoelectric power generation element of the present invention and the thermoelectric power generation module containing it, the thermal energy can be converted into electrical energy without imparting a temperature gradient to the system. That is, by using the thermoelectric power generation element or the thermoelectric power generation module of the present invention, it is possible to use geothermal, automobile exhaust heat, and factory exhaust heat to perform thermoelectric power generation without setting a temperature gradient in the system.

Furthermore, the thermoelectric power generation element of the present invention and the thermoelectric power generation module containing it can also be used as a thermoelectric power generation device or a thermal battery that converts surrounding thermal energy into electric energy as a power generation device or battery, and can be manufactured with a simple structure. Power generation device or battery.

Fig. 1 is a diagram schematically showing the thermoelectric power generation element of the present invention.

Fig. 2 is a graph showing the temperature dependence of the electron density (calculated value) of _{β-FeSi 2.}

Fig. 3 is a graph of electrical conductivity calculated from the measured value of the resistance value of the thermoelectric conversion material that generates thermally excited electrons and positive pores, that is _{, the temperature change of β-FeSi 2.}

_{Figure 4 shows the use of β-FeSi 2} as the thermoelectric conversion material (the first layer) that generates thermally excited electrons and positive pores, the _{use of CuZr 2} (PO ₄ ) ₃ as the electrolyte (the second layer), and the electron transport material ( Layer 3) A diagram of temperature-dependent power generation using an n-type silicon thermoelectric power generation element (Example 1).

_{Figure 5 shows the use of β-FeSi 2} as the thermoelectric conversion material (the first layer) that generates thermally excited electrons and positive pores, the _{use of CuZr 2} (PO ₄ ) ₃ as the electrolyte (the second layer), and the electron transport material ( Layer 3) Graph of the open voltage at 600°C of a thermoelectric power generation element using n-type silicon (Example 1).

_{Figure 6 shows the use of β-FeSi 2} as a thermoelectric conversion material (first layer) for generating thermally excited electrons and positive pores, _{CuZr 2} (PO ₄ ) ₃ as an electrolyte (second layer), and an electron transport material (Layer 3) A graph showing the results of measuring the electrochemical impedance at room temperature and 600°C using a thermoelectric power generation element using n-type silicon (Example 1).

_{Figure 7 shows the use of β-FeSi 2} as the thermoelectric conversion material (first layer) that generates thermally excited electrons and positive pores _{, and CuZr 2} (PO ₄ ) ₃ as the electrolyte (second layer), and as an electron transport material (Layer 3) A graph of the cell voltage of a thermoelectric power generation element using n-type silicon at 750°C and a constant voltage current of 5 μA (Example 2).

Figure 8 shows that the thermoelectric conversion material (first layer) that generates thermally excited electrons and positive pores uses β-FeSi ₂ and the electrolyte (second layer) uses CuZr ₂ (PO ₄ ) _{3 to} maintain the thermoelectric power generation element Graph of open voltage at 600°C (Example 3).

Figure 9 shows the maintenance of thermoelectric power generation elements using germanium as the thermoelectric conversion material (first layer) that generates thermally excited electrons and positive pores, and the electrolyte (second layer) using hexaammine cobalt (III) chloride aqueous solution Graph of the open voltage at 80°C (Example 4).

Figure 10 shows the maintenance of thermoelectric power generation elements using germanium as the thermoelectric conversion material (first layer) that generates thermally excited electrons and positive pores, and using vanadium(IV) sulfate n-hydrate aqueous solution as the electrolyte (second layer) Graph of the open voltage at 80°C (Example 5).

_{Figure 11 shows the use of β-FeSi 2} as the thermoelectric conversion material (the first layer) that generates thermally excited electrons and positive pores _{, and the use of RbCuCl 2} as the electrolyte (the second layer), and the use of the electron transport material (the third layer) ) A graph of the open voltage of a thermoelectric generating element using n-type silicon maintained at 190°C (Example 6).

[1] Thermoelectric power generation element

In the thermoelectric power generation element of the present invention, a first layer including a thermoelectric conversion material that generates thermally excited electrons and positive pores is laminated, and a second layer including a solid electrolyte or electrolyte solution in which charge transport ion pairs can move. Next, the valence electron charge potential of the thermoelectric conversion material in the first layer is more positive than the redox potential of the charge transport ion pair in the second layer. At the interface between the first layer and the second layer, the charge transport ion pair Among them, the more easily oxidized ions are oxidized and become the other ions.

In addition, the thermoelectric power generation element of the present invention may have a third layer containing an electron transporting material. The third layer is laminated on the side opposite to the laminated surface of the second layer of the first layer, and the electron transport The electron conduction band potential of the material is the same or positive as the conduction band potential of the semiconductor that generates thermally excited electrons and positive pores.

That is, the thermoelectric power generation element of the present invention includes (A) a first layer layered including a thermoelectric conversion material that generates thermally excited electrons and positive pores, and a solid electrolyte or an electrolyte solution in which charge transport ion pairs can move. The thermoelectric power generation element of the second layer, and (B) the first layer containing the thermoelectric conversion material, the second layer containing the charge transport ion pair as a movable solid electrolyte or electrolyte solution, and the first layer containing the There are two types of thermoelectric power generation elements in which the third layer of the electron transport material on the opposite side of the two layers is laminated.

In this specification, "thermoelectric conversion material" means a material that can excite electrons and positive pores by generating heat by heat. Specifically, semiconductors that generate thermally excited electrons and positive pores can be cited. In addition, in this specification, "charge transport ion pair" means an ion pair in which two stable ions of different valences are oxidized or reduced to the other ion, which can transport electrons and positive pores. They may also be ions of the same element with different valences.

The first layer may be a thermoelectric conversion layer including a thermoelectric conversion material that generates positive pores and electrons, the second layer may be a positive pore transport layer including a positive pore transfer material, and the third layer may include The electron transport layer of the electron transport material may also be used. The aforementioned thermoelectric conversion material is preferably a semiconductor, the aforementioned positive-electroporation material is preferably an electrolyte, and the electron transport material is preferably a semiconductor or a metal.

In addition, the thermoelectric power generation element of the present invention may also be a thermoelectric conversion layer containing (1) a thermoelectric conversion material that generates positive electricity holes and electrons, and (2) an electron transport layer and/or positive electricity transmission material that contains electron transport materials. The thermoelectric power generation element of the positive electric hole transport layer of the sexual material.

Basically, a positive electrode and a negative electrode are provided in various types of thermoelectric power generation elements. By applying heat, the thermoelectric conversion material generates a sufficient number of thermally excited electrons and positive pores for power generation. The negative electrode generates a potential difference and can generate a voltage. As an example of a general semiconductor, _{the temperature dependence of the excited electron density of β-FeSi 2} as shown in FIG. 2 shows that the excited electron density of the semiconductor increases as the temperature rises. The so-called number of thermally excited electrons and positive electron holes sufficient for power generation is actually expressed by the electron density per unit volume, as long as it is the same as the number of photoexcited electrons used in solar cells, for example, use The photoexcited electron density of amorphous silicon in solar cells is 10 ¹⁵ /m ³ (Non-Patent Document 2). That is, the thermoelectric conversion material used in the present invention can generate electricity under the condition ^{that the thermally excited electron density is 10 15} /m ^{3 or more.} In fact, in addition to this condition, the potential difference between the valence electron charge potential of the thermoelectric conversion material and the oxidation-reduction potential of the charge transport ion pair in the second layer, the electron moving speed in the first layer, and the respective values in the second layer Ease of movement of charge-transporting ions (In the case of a thermoelectric power generation element in which the third layer containing the electron transport material is laminated, it further includes the conduction charge potential of the thermoelectric conversion material and the electron conduction charge potential of the electron transport material in the third layer The potential difference and the electron moving speed in the third layer are related and determine the magnitude of the current generated. However, the temperature at which the thermally excited electron density becomes 10 ¹⁵ /m ³ is important. Next, it is also important that the number of excited thermionic and positive pores of the thermoelectric conversion material reaches a certain value or more. Specifically, in Examples 4 and 5, the generation current was confirmed by placing the germanium-containing thermoelectric power element as the thermoelectric conversion material on the first layer at 80°C. The thermally excited electrons and positive holes of germanium at 80°C were approximately It is 10 ¹⁸ /m ³ . _{In addition, in Example 6, the thermoelectric power generation element containing β-FeSi 2} was placed at 190°C as the first layer as a thermoelectric conversion material, and the generation current was confirmed. The thermally excited electrons and positive electricity _{of β-FeSi 2 at 190°C} The hole is about 10 ²¹ /m ³ . The number of thermally excited electrons and positive pores described here is calculated using the following calculation formula.

Here, Nc and Nv are the effective state density of the conduction band/valence cushion band, Eg is the energy band gap, k is the Boltzmann constant, and T is the temperature.

The temperature at which the thermoelectric power generation element of the present invention actually generates power is determined by the material’s inherent ease of electron movement, in addition to the temperature at which the thermoelectric conversion material in the first layer generates a sufficient number of thermally excited electrons and positive pores for power generation. Or the combination of the second layer (or the second layer and the third layer) affects the ease of electron movement at the interface with the first layer.

"Level 1"

The first layer constituting the thermoelectric power generation element of the present invention contains a thermoelectric conversion material. The first layer may contain components other than the thermoelectric conversion material as long as it can generate a sufficient number of thermally excited electrons and positive pores for power generation by applying an appropriate temperature. The aforementioned components are not listed as limited ones. Examples include binders (polyvinyl alcohol, methyl cellulose, acrylic resin, agar, etc.) that bind the thermoelectric conversion material to help the formation of the thermoelectric conversion material. Sintering aids (magnesium oxide, yttrium oxide, calcium oxide, etc.), etc. In addition, the solvent used in the manufacturing step may remain. The first layer used in the present invention substantially functions as a thermoelectric conversion layer.

The first layer can be produced by, for example, a painting method, a screen printing method, a spark plasma sintering method, a compression molding method, a sputtering method, a vacuum vapor deposition method, or a spin coating method. When the spin coating method is used, β-FeSi _{2 is} dispersed in a polar solvent such as acetone, and the solution is spin-coated on the third or second layer to form the first layer. In addition, as another method, β-FeSi ₂ is produced by spark plasma sintering method, and the obtained β-FeSi ₂ powder and conductive binder (for example, high-temperature conductive coating) are applied to the third or second layer It's also possible.

(Thermoelectric conversion material)

The thermoelectric conversion material contained in the first layer is not particularly limited as long as it can generate thermally excited electrons and positive holes by applying an appropriate temperature. For example, metal semiconductors, tellurium compound semiconductors, silicon germanium (Si -Ge) compound semiconductors, silicide compound semiconductors, skutterudites compound semiconductors, clathrate compound semiconductors, Heusler compound semiconductors, semi-Hausler compound semiconductors, metal oxide semiconductors, Organic semiconductors and other semiconductors. The semiconductor used in the present invention functions as a thermoelectric conversion material.

Examples of metal semiconductors include silicon semiconductors and germanium semiconductors.

Examples of tellurium compound semiconductors include Bi-Te compounds (for example, Bi ₂ Te ₃ , Sb ₂ Te ₃ , CsBi ₄ Te ₆ , Bi ₂ Se ₃ , Bi _0.4 Sb _1.6 Te ₃ , Bi ₂ (Se,Te) ₃ , (Bi,Sb) ₂ (Te,Se) ₃ , (Bi,Sb) ₂ Te ₃ , or Bi ₂ Te _2.95 Se _0.05 ), Pb-Te compounds (such as PbTe, or Pb _1-x Sn _x Te), SnTe , Ge-Te, AgSbTe ₂ , Ag-Sb-Ge-Te compounds (e.g. GeTe-AgSbTe ₂ (TAGS)), Ga ₂ Te ₃ , (Ga _1-x In _x ) ₂ Te ₃ , Tl ₂ Te-Ag ₂ Te, Tl ₂ Te-Cu ₂ Te, Tl ₂ Te-Sb ₂ Te ₃ , Tl ₂ Te-Bi ₂ Te ₃ , Ti ₂ Te-GeTe, Ag ₈ Tl ₂ Te ₅ , Ag ₉ TlTe ₅ , Tl ₉ BiTe ₆ , Tl ₉ SbTe ₆ , Tl ₉ CuTe ₅ , Tl ₄ SnTe ₃ , Tl ₄ PbTe ₃ , or Tl _0.02 Pb _0.98 Te.

Examples of silicon germanium (Si-Ge) compound semiconductors include Si _x Ge _1-x or SiGe-GaP.

Examples of silicide compound semiconductors include β-FeSi ₂ compounds (for example, β-FeSi ₂ , Fe _1-x Mn _x Si ₂ , Fe _0.95 Mn _0.05 Si _(2-y) Al _y , FeSi _(2-y) Al _y , Fe _1-y Co _y Si ₂ , Mg ₂ Si, MnSi _1.75-x , Ba ₈ Si ₄₆ , Ba ₈ Ga ₁₆ Si ₃₀ , or CrSi ₂ .

As a skutterudite compound semiconductor, there can be mentioned the formula TX ₃ (where T is a transition metal selected from the group consisting of Co, Fe, Ru, Os, Rh, and Ir, and X is P, As, and A compound represented by a nitrogen group element (pnictogen) selected from the group consisting of Sb, the derivative of the aforementioned compound has the formula RM ₄ X ₁₂ (where R is Sc, Y, La, Ce, Pr, Nd, Pm, Sm Rare earths selected from the group consisting of, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu, M is selected from the group consisting of Fe, Ru, Os, and Co, X is P , As, and Sb), Yb _y Fe _4-x Co _x Sb ₁₂ , (CeFe _{3 CoSb 12} ) _1-x (MoO ₂ ) _x, or (CeFe _{3 CoSb 12} ) _1-x (WO ₂ ) _x .

As a clathrate compound semiconductor, the formula M ₈ X ₄₆ (M is selected from the group consisting of Ca, Sr, Ba, and Eu, and X is selected from the group consisting of Si, Ge, and Sn) The compound represented is a compound represented by the formula (II) ₈ (III) ₁₆ (IV) ₃₀ (wherein II is a group II element, III is a group III element, and IV is a group IV element), which is a derivative of the aforementioned compound. As the compound of the aforementioned formula (II) ₈ (III) ₁₆ (IV) ₃₀ , for example, Ba ₈ Ga _x Ge _46-x , Ba _8-x (Sr,Eu) _x Au ₆ Ge ₄₀ , or Ba _{8- x} Eu _x Cu ₆ Si ₄₀ .

Examples of Heusler compound semiconductors include Fe ₂ VAl, (Fe _1-x Re _x ) ₂ VAl, or Fe ₂ (V _1-xy Ti _x Ta _y )Al.

As a semi Haussler compound semiconductor include compounds of formula MSiS _n (wherein M is the group Ti, Zr, and Hf and selected) represented by the formula MNiS _n (wherein M is Ti or Zr) as The compound represented by the formula MCoSb (where M is selected from the group consisting of Ti, Zr, and Hf), or the formula LnPdX (where Ln is selected from the group consisting of La, Gd, and Er, X is Compound represented by Bi or Sb).

Examples of metal oxide semiconductors include In ₂ O _{3 -SnO 2} , (CaBi)MnO ₃ , Ca(Mn, In)O ₃ , Na _x V ₂ O ₅ , V ₂ O ₅ , ZnMnGaO ₄ and its derivatives , LaRhO ₃ , LaNiO ₃ , SrTiO ₃ , SrTiO ₃ : Nb, Bi ₂ Sr ₂ Co ₂ O _y , Na _x CoO ₂ , NaCo ₂ O ₄ , CaPd ₃ O ₄ , formula Ca _a M1 _b Co _c M2 _d Ag _e O _f (where M1 is selected from the group consisting of Na, K, Li, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Pb, Sr, Ba, Al, Bi, Y and rare earths One or more elements, M2 is one or more elements selected from the group consisting of Ti, V, Cr, Mn, Fe, Ni, Cu, Mo, W, Nb, Ta and Bi, 2.2 Compounds represented by ≦a≦3.6, 0≦b≦0.8, 2≦c≦4.5, 0≦d≦2, 0≦e≦0.8, 8≦f≦10), ZnO, Na(Co,Cu) ₂ O _4. ZnAlO, Zn _1-x Al _x O, or La _1.98 Sr _0.02 CuO ₄ .

Examples of organic semiconductors include organic perovskite (perovskite), polyaniline, polyacetylene (polyacetylene), polythiophene, polyalkylthiophene (thiophene), or polypyrrole.

Other thermoelectric conversion compounds include alloys containing Co and Sb (for example, CoSb _{3 , CeFe 3 CoSb 12} , CeFe _{4 CoSb 12} , or YbCo ₄ Sb ₁₂ ), alloys containing Zn and Sb (for example, ZnSb, Zn ₃ Sb ₂ or Zn ₄ Sb ₃ ), alloys containing Bi and Sb (e.g. Bi ₈₈ Sb ₁₂ ), CeInCu ₂ , (Cu, Ag) ₂ Se, Gd ₂ Se ₃ , CeRhAs, or CeFe ₄ Sb ₁₂ , Li _7.9 B ₁₀₅ , BaB ₆ , SrB ₆ , CaB ₆ , AlPdRe compounds (e.g. Al ₇₁ Pd ₂₀ (Re _1-x Fe _x ) ₉ ), AlCuFe quasi-crystalline, Al _82.6-x Re _17.4 Si _x1/1 -legislation approximate crystalline, _{YbAl 3} , YbMn _x Al ₃ , β-CuAgSe, B ₄ C/Ba ₃ C, (Ce _1-x La _x )Ni ₂ , or (Ce _1-x La _x )In ₃ .

The temperature imparted to the thermoelectric conversion material can be appropriately selected as the temperature at which the respective thermoelectric conversion material generates a sufficient number of thermally excited electrons and positive pores for power generation. In other words, in the present invention, by giving the thermoelectric conversion material a temperature that generates a sufficient amount of thermally excited electrons and positive pores for power generation, a voltage can be generated in the thermoelectric power generation element. The so-called number of thermally excited electrons and positive pores sufficient for power generation is actually expressed in terms of electron density, as long as it is the same as the number of photoexcited electrons used in solar cells, such as those used in solar cells. The number of photoexcited electrons of amorphous silicon is 10 ¹⁵ /m ³ . That is, in the thermoelectric conversion material used in the present invention, at a temperature at which the thermally excited electron density is 10 ¹⁵ /m ³ or more, a sufficient number of thermally excited electrons and positive pores for power generation can be generated, and it can be carried out at a temperature above this temperature. Power generation.

As a general embodiment of a semiconductor, β-FeSi ₂ shown in FIG. 2 of the excited electron density dependence of the apparent temperature, semiconductor excited electron density increases with increasing temperature. The density of excited electrons at a specific temperature, that is, the number of thermally excited electrons and positive pores, is calculated by calculating the aforementioned "number of thermally excited electrons", which is a value inherent to the material. That is, as long as the person is familiar with the art, the "temperature at which the thermally excited electron density becomes 10 ¹⁵ /m ³ or more" can be calculated from the technical common sense in the technical field of the present invention and the description in this specification.

For example, the germanium used as the thermoelectric conversion material in Examples 4 and 5 generates thermally excited electrons and positive pores of ^{about 10 18} /m ^{3 at 80° C. when power generation starts.} On the other hand, β-CuAgSe, a semiconductor, generates thermally excited electrons and positive pores of ^{about 10 18} /m ^{3 at 10°C.} Therefore, when β-CuAgSe is used as a thermoelectric conversion material, there is a possibility of generating electricity at room temperature.

The upper limit of the temperature imparted by the respective thermoelectric conversion materials is not particularly limited. As the temperature of the thermoelectric conversion material increases, the number of thermally excited electrons and positive pores also increases. That is, the upper limit of the temperature given to the thermoelectric conversion material is determined by the melting point of the heat conversion material or the physical upper limit temperature of the thermoelectric power generation device, thermal battery, or thermoelectric power module used.

In addition, the temperature range in which the thermoelectric conversion material can generate thermally excited electrons and positive pores can be specified through experiments. The operating temperature of the thermoelectric conversion material and the thermoelectric generating element used in the present invention depends on the number of thermally excited electrons and positive holes at that temperature inherent to the semiconductor used, but the selection can be determined by measuring the resistance value or electrical conductivity Find out. Specifically, as shown in Reference Example 1, the temperature of β-FeSi _{2 may be increased by heating β-FeSi 2} , and the temperature range may be specified by measuring the resistance value of β-FeSi _2. As shown in Fig. 3, _{the electrical conductivity of β-FeSi 2} rises rapidly after exceeding 190°C. Due to the rapid increase in electrical conductivity, it is known that a sufficient number of thermally excited electrons and positive holes for power generation are generated near this temperature. That is, those who are familiar with the art can specify whether the thermoelectric conversion material can generate a sufficient number of thermally excited electrons and positive holes for power generation by conducting the experiment of Reference Example 1, and further, can specify the thermoelectricity The temperature range in which the conversion material generates a sufficient number of thermally excited electrons and positive pores for power generation.

"Level 2"

The second layer constituting the thermoelectric power generation element of the present invention contains a solid electrolyte or an electrolyte solution.

The second layer is not particularly limited as long as the charge transport ion pair can move. That is, the second layer is not particularly limited as long as it can transport positive pores generated in the thermoelectric conversion material, and may contain components other than a solid electrolyte or an electrolyte solution. The aforementioned components are not listed as limited ones. For example, polar solvents (water, methanol, toluene, tetrahydrofuran, etc.) that dissolve or disperse electrolytes, and binders (polyvinyl alcohol, Methyl cellulose, acrylic resin, agar (agar), etc.), sintering aids (magnesium oxide, yttrium oxide, calcium oxide, etc.) that contribute to the formation of conveyable materials. The second layer used in the present invention essentially functions as a positive-electroporation transport layer.

In addition, "charge transport ion pair" means two stable ions with different valences. One ion is oxidized or reduced to become the other ion, which can transport electrons and positive pores. Furthermore, the second layer may contain ions other than the charge transport ion pair.

The second layer can be produced by, for example, a painting method, a screen printing method, a sputtering method, a vacuum vapor deposition method, a sol-gel method, or a spin coating method. For example, CuZr ₂ (PO ₄ ) ₃ described later is produced by a sol-gel method, and the obtained sol is prepared into a layered second layer using a painting method.

In addition, when the electrolyte is an electrolyte solution (liquid electrolyte), the second layer is a liquid phase. When the second layer is a liquid phase, the second layer of the thermoelectric power generation element is preferably modulated when producing a thermoelectric power generation device, a thermal battery, or a thermoelectric power generation module. That is, by providing a tank for holding an electrolyte solution (liquid electrolyte), the second layer can be produced.

(Electrolyte)

As the electrolyte, a solid electrolyte or an electrolyte solution is contained. The electrolysis value is not particularly limited as long as it can transport two ions of the ion pair.

That is, for the electrolyte used in the second layer, the redox potential of the valence electron charge potential of the thermoelectric conversion material used in the thermoelectric power element is at an appropriate position, as long as the charge transport ion pair can communicate in the electrolyte. Specially limited. In addition, the electrolyte is preferably one that is physically and chemically stable at a temperature at which the thermoelectric conversion material generates a sufficient number of thermally excited electrons and positive pores for power generation.

As the electrolyte, depending on its aspect, it may be a solid electrolyte or an electrolyte solution (liquid electrolyte). Here, depending on the temperature, the electrolyte has the form of an electrolyte solution (liquid electrolyte) and also a form of a solid electrolyte. That is, the compound contained in the electrolyte solution (liquid electrolyte) and the compound contained in the solid electrolyte are repeated. In addition, the electrolyte contains molten salt, ionic liquid, or deep eutectic solution Media (Deep Eutectic Solvents, DES), etc. The so-called molten salt means that a salt composed of cations and anions is in a molten state. Although the molten salt has a relatively low melting point (for example, below 100°C or below 150°C), it is called ionic liquid. In the specification, molten salt in a solid state is called a solid electrolyte, and a solution state is called an electrolyte solution (liquid electrolyte). Specific examples are given below for the electrolyte solution (liquid electrolyte), solid electrolyte, and molten salt, and these are repeated.

The electrolyte solution is a temperature at which the thermoelectric conversion material in the first layer generates a sufficient number of thermally excited electrons and positive pores for power generation, and a solution (liquid) state is used. Specifically, the electrolyte solution is not particularly limited. Examples include methanol ion, hydrogen ion, ammonia ion, pyridine ion, lithium ion, sodium ion, potassium ion, calcium ion, magnesium ion, aluminum ion, iron ion, and copper ion. Ion, zinc ion, cobalt ion, fluoride ion, cyanide ion, thiocyanate ion, chloride ion, acetate ion, sulfate ion, carbonate ion, phosphate ion, bicarbonate ion, bromide ion.

In the solid electrolyte, the thermoelectric conversion material in the first layer generates a sufficient number of thermally excited electrons and positive pore temperatures for power generation, and is a solid state that can move inside using a charge transport ion pair. It is possible to use a thermoelectric power generation element that uses a high-temperature solid electrolyte to generate thermally excited electrons and positive pores at a high temperature. Specifically, the solid electrolyte is not particularly limited, and examples include sodium ion conductors, copper ion conductors, lithium ion conductors, silver ion conductors, hydrogen ion conductors, strontium ion conductors, aluminum ion conductors, Fluoride ion conductor, chloride ion conductor, or oxide ion conductor, etc. As specific solid electrolytes, for example, RbAg ₄ I ₅ , Li ₃ N, Na ₂ O‧11Al ₂ O ₃ , Sr-β alumina, Al(WO ₄ ) ₃ , PbF ₂ , PbCl ₂ , (ZrO ₂ ) _0.9 (Y ₂ O ₃ ) _0.1 , (Bi ₂ O ₃ ) _0.75 (Y ₂ O ₃ ) _0.25 , CuZr ₂ (PO ₄ ) ₃ , CuTi ₂ (PO ₄ ) ₃ , Cu _x Nb _1-x Ti _{1+ x} (PO ₄ ) ₃ , H _0.5 Cu _0.5 Zr ₂ (PO ₄ ) ₃ , Cu _1+x Cr _x Ti _2-x (PO ₄ ) ₃ , Cu _0.5 TiZr(PO ₄ ) ₃ , CuCr ₂ Zr(PO ₄ ) ₃ , Cu ₂ ScZr(PO ₄ ) ₃ , CuSn ₂ (PO ₄ ) ₃ , CuHf ₂ (PO ₄ ) ₃ , Li ₇ La ₃ Zr ₂ O ₁₂ , Li ₇ La ₃ Zr _2-x Nb _x O ₁₂ , Li ₇ La ₃ Zr _2-x Ta _x O ₁₂ , Li ₅ La ₃ Ta ₂ O ₁₂ , Li _0.33 La _0.55 TiO ₃ , Li _1.5 Al _0.5 Ge _1.5 P ₃ O ₁₂ , Li _1.3 Al _0.3 Ti _1.7 P ₃ O ₁₂ , Li ₃ PO ₄ (LiPON), Li ₄ SiO ₄ -Li ₃ PO ₄ , Li ₄ SiO ₄ , or Li ₃ BO ₃ and so on.

In addition, as the solid electrolyte or electrolyte solution, a molten salt can be used. In the case of thermoelectric power generation elements used at relatively low temperatures, ionic liquids can also be used. As the ionic liquid, a deep eutectic solvent (Deep Eutectic Solvents, DES) can be used.

Examples of molten salts include at least 1 selected from the group consisting of imidazoline cations, pyridine cations, piperidine cations, pyrrolidine cations, phosphonium cations, morpholinium cations, sulfonium cations, and ammonia cations. Kinds of cations, as well as carboxylic acid anions, sulfonic acid anions, halogen anions, tetrafluoroborate, hexafluorophosphate, bis (trifluoromethanesulfonyl) amide, and bis (fluorosulfonyl) amide At least one anion selected from the constituent group. The electrolyte used in the present invention functions as a positive-electroporation transmission material.

"The oxidation reaction of ions at the interface between the first layer and the second layer"

In the present invention, the valence electron charge potential of the thermoelectric material in the first layer is more positive than the redox potential of the charge transport ion pair in the second layer (electrolyte). That is, at the interface between the first layer and the second layer of the present invention, the ion that is more easily oxidized among the charge transport ion pairs is oxidized to become the other ion. The potential difference between the oxidation-reduction potential of the charge transport ion pair in the electrolyte and the valence electron potential of the thermoelectric conversion material is not particularly limited as long as the effects of the present invention can be obtained, and it is preferably 0 to 1.0 V, more preferably 0.05 to 0.5 V is more preferably 0.05 to 0.3V. For example, the potential difference between _{the oxidation-reduction potential of CuZr 2} (PO ₄ ) ₃ (Cusicon, copper ion conductor) and _{the valence electron charge potential of β-FeSi 2 is about 0.05V.}

For those who have measured the redox potential of the charge transport ion pair and the valence electron potential of the thermoelectric conversion material, those who are familiar with the art can choose the appropriate value for the thermoelectric conversion material from the values of these redox potential and valence electron potential. Ion, select the electrolyte in which the ion can move. In addition, for materials in which the valence electron charge potential of the thermoelectric conversion material and the oxidation-reduction potential of the charge transport ion pair are not clear, the valence electron charge potential of the thermoelectric conversion material and the oxidation-reduction potential of ions can be measured. That is, as long as the person is familiar with the art, the appropriate charge transport ion pair electrolyte can be appropriately selected according to the selected thermoelectric conversion material.

In addition, the phrase "the valence electron charge potential of the thermoelectric conversion material in the first layer is more positive than the redox potential of the charge transport ion pair in the second layer (electrolyte)" means "the valence electron charge potential of the thermoelectric conversion material , The oxidation-reduction potential is in the right position.”

"Level 3"

The thermoelectric power generation element of the present invention may have a third layer laminated on the first layer. The third layer is laminated on the opposite side of the laminated surface (interface) of the first layer and the second layer. The third layer contains electron transport materials. The third layer has only to be capable of transporting thermally excited electrons generated in the thermoelectric conversion material, and may contain components other than the electron transport material. The aforementioned components are not listed as limited ones. Examples include binding agents (polyvinyl alcohol, methyl cellulose, acrylic resin, agar, etc.) that bind electron transport materials to help the formation of electron transport materials. Sintering aids (magnesium oxide, yttrium oxide, calcium oxide, etc.), etc. In addition, the solvent used in the manufacturing step may remain. The third layer used in the present invention substantially functions as an electron transport layer.

In the thermoelectric power generation element of the present invention, the electron conduction band potential of the electron transport material is the same as or positive as the conduction band potential of the thermoelectric conversion material in the first layer. That is, the electron transport material can transport thermally excited electrons.

The third layer can be produced by, for example, a painting method, a screen printing method, a sputtering method, a vacuum vapor deposition method, a single crystal growth method, or a spin coating method. When the spin coating method is used, the oxadiazole derivative is dissolved in a polar solvent such as acetone, and the solution is spin-coated on the substrate or the first layer to form the third layer. For example, the third layer of n-type silicon described later can be obtained by a single crystal growth method, and this third layer of n-type silicon can be used as a substrate, and the first layer can be laminated.

(Electronic transport material)

The electron transport material used in the third layer is not particularly limited as long as its electron conduction band potential is the same as or positive for the conduction band potential of the thermoelectric conversion material in the first layer. The potential difference between the electron conduction band potential of the electron transport material in the third layer and the conduction band potential of the thermoelectric conversion material in the first layer is not particularly limited as long as the effects of the present invention can be obtained, and it is preferably 0.01 to 1V, and more Preferably, it is 0.01~0.5V, more preferably is 0.01~0.3V, and most preferably is 0.05~0.2V. For example, the potential difference between the conduction band potential of n-type silicon and the conduction band potential of β-FeSi ₂ , that is, the electron conduction band potential is about 0.01V.

For those who have measured the conduction band potential of the thermoelectric conversion material and the electron conduction band potential of the electron transport material, those skilled in the art can choose the electron transport material suitable for the thermoelectric conversion material in the first layer from the values of these potentials. In addition, for materials in which the conduction band potential of a semiconductor and the electron conduction band potential of an electron transport material are not clear, these potentials can be measured by, for example, electrochemical measurement or XPS of reverse photoelectron spectroscopy. That is, as long as the person is familiar with the art, according to the thermoelectric conversion material used in the first layer of the thermoelectric power generation element, an appropriate electron transport material can be appropriately selected.

As the electron transport material, semiconductors and metals can be cited. Examples of specific electron transport materials include N-type metal oxides containing at least one selected from the group consisting of niobium, titanium, zinc, tin, vanadium, indium, tungsten, tantalum, zirconium, molybdenum, and manganese, N-type metal sulfide, halogenated alkali metal, alkali metal, or electron transporting organic substance. More specifically, titanium oxide, tungsten oxide, zinc oxide, niobium oxide, indium oxide, tin oxide, gallium oxide, tin sulfide, indium sulfide, zinc sulfide, or SrTiO ₃ can be cited. In addition, examples of electron transporting organic substances include N-type conductive polymers, N-type low-molecular organic semiconductors, π-electron conjugated compounds, and surfactants; specific examples include oxadiazole derivatives, three Azole derivatives, perylene derivatives, or quinolinol metal complexes, polyparaphenylene vinylene containing cyano groups, boron-containing polymers, 2,9-dimethyl-4,7-biphenyl- 1,10-Bathocuproine, 4,7-diphenyl-1,10-phenanthroline, aluminum hydroxyquinoline, oxadiazole compound, benzimidazole compound, Naphthalene tetracarboxylic acid compounds, perylene derivatives, phosphine oxide compounds, thiophosphine compounds, fluorine-containing phthalocyanines, fullerenes and their derivatives, phenylacetylene polymers, perylene tetracarboxylic acid Amine derivatives. As a semiconductor, the "semiconductor" described in the item of the aforementioned "first layer" can be used as an electron transport material.

"Thermoelectric power generation element"

The structure of the thermoelectric power generation element of the present invention and its power generation mechanism will be explained using FIG. 1. In the thermoelectric power generation element, sandwiching the first layer containing the thermoelectric conversion material, there are a third layer containing an electron transport material and a second layer containing an electrolyte. An electrode (negative electrode) is provided on the third layer, and an electrode (positive electrode) is provided on the second layer. Then, by connecting these electrodes to apply a load, electrons flow from the negative electrode to the positive electrode.

Specifically, the thermoelectric conversion material is a material that can generate a sufficient number of thermally excited electrons and positive pores for power generation at a temperature above a certain temperature. quality. That is, if an appropriate temperature is applied to the thermoelectric conversion material, a sufficient number of thermally excited electrons and positive holes for power generation are generated. The electron conduction band potential of the electron transport material contained in the third layer adjacent to the first layer is positive for the conduction band potential of the thermoelectric conversion material, so electrons move from the first layer to the third layer and then to the electrode. On the other hand, the oxidation-reduction potential of the electrolyte contained in the second layer adjacent to the first layer is negative for the valence electron potential of the thermoelectric conversion material in the first layer, so the positive pores are transported from the first layer. To the electrode (positive electrode). That is, in the electrolyte, redox of ions occurs, electrons are transported from the electrode to the first layer, and positive pores are transported from the first layer to the electrode (positive electrode). With this mechanism, electrons move from the negative electrode to the positive electrode to generate electricity. That is, by combining thermoelectric conversion materials, electron transport materials, and electrolytes that satisfy such conditions, an intensified thermoelectric power generation element can be produced.

"According to the power generation mechanism of the first and second floors"

As shown in Example 3, even if the third layer is missing and only the first and second layers are present, electricity can be generated. When generating electricity based on the first layer and the second layer, the thermoelectric conversion material of the first layer directly transfers electrons to the electrode to generate electricity.

[2] Power generation method

In the power generation method of the present invention, the thermoelectric power generation element is placed in an environment where the thermoelectric conversion material that generates the thermally excited electrons and positive pores in the first layer has ^{a temperature of 10 15} /m ³ or higher. To generate electricity.

In the power generation method of the present invention, the thermally excited electron density is preferably 10 ¹⁵ /m ³ or more, more preferably 10 ¹⁸ /m ³ or more, still more preferably 10 ²⁰ /m ³ or more, most preferably 10 ²² /m ³ or more. The higher the thermally excited electron density, the higher the power generation efficiency can be obtained. The thermally excited electron density differs depending on the thermoelectric conversion material, and the thermally excited electron density can be calculated by the formula described in the item "[1] Thermoelectric power generation element" above.

In addition, the temperature of the power generation method of the present invention is such that the thermally excited electron density is preferably 10 ¹⁵ /m ³ or more, more preferably 10 ¹⁸ /m ³ or more, and still more preferably 10 ²⁰ /m ³ or more The best temperature is 10 ²² /m ³ or more. The temperature of power generation basically differs depending on the thermoelectric conversion material. It can be calculated by the aforementioned thermally excited electron density, and/or measured by experiments as described in the item of "[1] Thermoelectric power generation element". The temperature range within which thermally excited electrons and positive pores can be generated is determined.

That is, as long as the person is familiar with the art, the temperature of power generation can be appropriately determined based on the technical common sense in the technical field of the present invention and the description in this specification. In addition, the power generation temperature of the power generation method of the present invention is preferably a temperature at which the charge transport ion pair can communicate in the electrolyte.

The specific temperature is not particularly limited. For example, it is 50°C or higher, preferably 60°C or higher, more preferably 80°C or higher, and still more preferably 100°C or higher. The upper limit of the temperature is not particularly limited as long as it is a temperature at which the charge transport ion pair can communicate in the electrolyte. For example, it is 1500°C or lower, preferably 1000°C or lower.

In addition, the temperature at which the thermoelectric power generation element of the present invention actually generates electricity, in addition to the temperature at which the thermoelectric conversion material in the first layer generates a sufficient number of thermally excited electrons and positive holes for electricity generation, is also facilitated by the movement of electrons inherent in the material. It is determined by the degree of electron movement at the interface with the first layer affected by the combination of the second layer (or the second layer and the third layer). These conditions can be appropriately reviewed.

[3] Thermoelectric power generation device, thermal battery and thermoelectric power generation module

The thermoelectric power generation device of the present invention and the thermoelectric power generation element including the present invention preferably include a positive electrode and/or a negative electrode. In addition, the thermal battery of the present invention and the thermoelectric power generation element including the present invention preferably include a positive electrode and/or a negative electrode. Furthermore, the thermoelectric power generation module of the present invention and the thermoelectric power generation element of the present invention preferably include a positive electrode and/or a negative electrode. The third layer of the thermoelectric power generation element used in the thermoelectric power generation device, the thermal battery, and the thermoelectric power generation module of the present invention can take the role of the negative electrode, and the second layer can take the role of the positive electrode. Among them, in thermoelectric power generation devices, thermal batteries, and thermoelectric power generation modules, it is preferable to have a positive electrode and a negative electrode.

The term "thermal battery" in this specification refers to the thermoelectric power generation element of the present invention, which generates electricity by giving the semiconductor (thermoelectric conversion material) of the thermoelectric power generation element a temperature that can generate thermally excited electrons and positive pores. Battery. In other words, the so-called thermal battery is a "battery that can generate electricity with a heat source", which is different from the previous "battery that generates electricity from a high-temperature part and a low-temperature part".

"electrode"

The positive electrode and the negative electrode are not particularly limited as long as they can transport electrons. Examples include titanium, gold, platinum, silver, copper, tin, tungsten, niobium, tantalum, stainless steel, aluminum, graphite, alkene, molybdenum, and indium. , Vanadium, rhodium, niobium, chromium, nickel, carbon, alloys of these, or combinations of these. In addition, the same material may be used for the positive electrode and the negative electrode.

The positive electrode and the negative electrode may be provided in the form of a wire, and they may be provided as a positive electrode layer or a negative electrode layer. In the case of the positive electrode layer or the negative electrode layer, it can be produced by a vacuum evaporation method or a spin coating method. By providing a negative electrode on the third layer side of the thermoelectric power element and a positive electrode on the second layer side, electrons move from the negative electrode to the positive electrode to generate electricity.

[4] Thermoelectric power generation method

The thermoelectric power generation method of the present invention includes a step of installing the thermoelectric power generation module in a place where heat is generated, and a step of heating the thermoelectric power generation module by heat to generate electricity.

"Setup steps for thermoelectric power generation modules"

In the step of installing the thermoelectric power generation module, the thermoelectric power generation module of the present invention is installed in a place where heat is generated.

The place where the heat is generated is not particularly limited as long as it is a place where the thermoelectric conversion material generates a sufficient amount of excited electrons and heat above the temperature of the positive pores for power generation. However, from the viewpoint of efficient power generation, a place with a relatively high temperature is better, that is, as a place where heat is generated For example, a place where geothermal heat is generated, or a place where exhaust heat is generated such as a factory.

Geothermal is not limited to the heat in the soil, but also includes hot water or steam heated by geothermal. Furthermore, geothermal heat also includes hot water or steam such as sea, lake, or river heated by geothermal heat.

The exhaust heat is not particularly limited, and examples include exhaust heat from steel furnaces, waste incineration plants, substations, subways, and automobiles. In particular, the exhaust heat of a steelmaking furnace or a waste incineration plant with large energy is usually discharged without using its energy, which is suitable for reuse by the thermoelectric power generation method of the present invention.

"Power Generation Project"

In power generation projects, electricity is generated by heating the thermoelectric power generation module of the present invention. By the heat generated in the aforementioned heat-generating place, the thermoelectric conversion material of the thermoelectric power generation module is heated to a temperature higher than the temperature of a sufficient number of excited electrons and positive holes for power generation, and electricity can be generated from the thermoelectric power generation module.

[Example]

Hereinafter, the present invention will be specifically explained through examples, but the present invention is not limited to these ranges.

"Reference Example 1"

A β-FeSi ₂ sintered body (square with a side of 0.8 cm and a thickness of 2 mm) was set on a hot plate, and the temperature dependence of the resistance value was measured by the four-terminal method. It was confirmed that the resistance value decreased with increasing temperature, and the increase in electrical conductivity calculated from this value was confirmed (Figure 3). In addition, if it exceeds 190°C, the electrical conductivity increases rapidly. The rapid change of this reduction means that at a time point exceeding 190°C, a huge number of thermally excited electrons and positive pores are generated _{in the β-FeSi 2 sintered body.}

"Example 1"

15mm的成形體，以800℃、30min、55MPa的條件進行SPS燒結得到β-FeSi₂。此外，把CuO、ZrOCl‧8H₂O、以及(NH₄)H₂PO₄以配合化學量論比的方式進行秤重，關於蒸餾水、CuO使溶解於HNO₃水溶液之後，進行混合、攪拌。在80℃乾燥1日半後，在800℃加熱8小時，得到CuZr₂(PO₄)₃(Cusicon、銅離子傳導體)。 1.68g of α-Fe ₂ Si ₅ powder is uniaxially pressed at 250kgf for 1 minute to produce

The 15mm molded body was subjected to SPS sintering at 800°C, 30 min, and 55 MPa to obtain β-FeSi ₂ . In addition, CuO, ZrOCl‧8H ₂ O, and (NH ₄ )H ₂ PO ₄ were weighed in a stoichiometric manner, and the distilled water and CuO were dissolved in the HNO ₃ aqueous solution, and then mixed and stirred. After drying at 80°C for a day and a half, it was heated at 800°C for 8 hours to obtain CuZr ₂ (PO ₄ ) ₃ (Cusicon, copper ion conductor).

The n-type silicon (n-Si) (100) (ρ=1-10Ω) cut into 1.0cm×1.0cm squares was subjected to HF treatment for 5 minutes, and then β-FeSi ₂ obtained by the SPS sintering method was applied 0.0309 g of the ground powder is mixed with 0.0785 g of a conductive binder (Pyro-Duct597) to bond them together. Then dry at room temperature for 2 hours, dry at 93°C for 2 hours, put Cusicon in a 20mmΦ mold, and then set β-FeSi ₂ and n-Si with β-FeSi ₂ below, and set it at 50 MPa Pressurize for 3 minutes. After removing the excess Cusicon, Cusicon becomes 0.1929g. The obtained sample was sintered at 400°C for 6 hours. The heating and cooling speed is 2 ℃/min.

In the sintered sample, platinum (Pt) wires were mounted as electrodes on the Cusicon side and the n-Si side using conductive silver paste. Clamp it with a glass slide and reinforce it with an insulating adhesive (Aron Ceramic). Similarly, they were dried at room temperature and 93°C for 2 hours.

The manufactured samples are set in the electric furnace. When the Cusicon side is used as the working electrode and the n-Si side is used as the counter electrode, the natural potential at room temperature is 0.035V. The current change when the voltage is changed to the natural voltage is measured by the 2-terminal method. The heating rate is 5°C/min. The temperature is increased to 600°C. It was confirmed that a rectifying current that depends on the temperature is generated (Figure 4).

The CV curve is measured while keeping the temperature at 600°C. The scan rate is 10mV/sec. As a result, the battery characteristics can be obtained with the third layer/first layer/second layer (Figure 5).

In addition, in the aforementioned connection, electrochemical impedance measurement was performed at room temperature and 600°C (Figure 6). The decrease in resistance value was confirmed at 600°C.

"Example 2"

After the n-type silicon (n-Si) (100) (ρ=1-10Ω) cut into 1.0cm×0.5cm squares is subjected to HF treatment for 5 minutes, 0.0785g of silver paste is applied to bond it with _{The β-FeSi 2} powder obtained by the SPS sintering method in the same step in Example 1 was pulverized 0.0309 g. Then dry at room temperature for 2 hours and at 93°C for 2 hours, set β-FeSi _{2 and n-Si in a mold of 20 mmΦ with β-FeSi 2} on top, and put them in the same way as in Example 1. The Cusicon produced in the procedure was pressurized at 50 MPa for 3 minutes. After removing the excess Cusicon, Cusicon becomes 0.1929g. The obtained sample was sintered at 400°C for 6 hours. The rate of heating and cooling is 2°C/min.

For the sintered sample, platinum (Pt) wires were installed as electrodes on the Cusicon side and the n-Si side using silver paste. Clamp it with a glass slide and reinforce it with an insulating adhesive (Aron Ceramic). Similarly, they were dried at room temperature and 93°C for 2 hours.

The manufactured samples are set in the electric furnace. The Cusicon side is used as the working electrode and the n-Si side is used as the counter electrode, and the heating rate is 5°C/min to 600°C. While keeping the temperature at 600°C, the current was fixed at 100nA and the voltage change over time was measured. In this test, it was confirmed that the electricity was continuously generated at a constant current for more than 6 hours (Figure 7). Thereafter, CV measurement was performed from 0.1V to -0.1V at a scan rate of 10mV/sec. As a result, the battery characteristics can be obtained with the third layer/first layer/second layer.

"Example 3"

As an example of the combination of the first layer and the second layer, _{the measurement results of β-FeSi 2} and Cusicon are shown.

Put 0.0797g of β-FeSi2 powder obtained by the SPS sintering method in the same procedure as in Example 1 into a 10mmΦ mold, and then pat to make it smooth, then place 0.2356g in the same procedure as in Example 1. The produced Cusicon was pressurized at 100 MPa for 5 minutes. The obtained sample was sintered at 400°C for 6 hours. The rate of heating and cooling is 2°C/min.

In the sintered sample, platinum (Pt) wires were installed as electrodes on the Cusicon side and the β-FeSi _{2 side using conductive silver paste.} Furthermore, it was sandwiched between glass slides and reinforced with an insulating adhesive (Aron Ceramic), and then dried at room temperature and 93°C for 2 hours.

The prepared samples were set in an electric furnace, and the Cusicon side was used as the working electrode, the β-FeSi2 side was used as the counter electrode, and the CV measurement was performed at a potential sweep rate of 10 mV/sec while keeping the temperature at 600°C (Figure 8). As a result, the battery characteristics can be obtained with the first layer/second layer at 600°C.

"Example 4"

In this example, germanium was used as the semiconductor (first layer), and an aqueous solution of cobalt (III) chloride hexaammine was used as the electrolyte (second layer) to fabricate a thermoelectric power generation element.

A spacer of Kapton tape (12.5×15×0.1mm thick) with a diameter of 6mm hole is adhered to a germanium semiconductor of 25×15×0.5mm, and the degassed (0.15M sodium sulfate + 4mM hexaammine cobalt trichloride ) 2.4 mL of the aqueous solution was dropped, and it was sandwiched with a 25×15 mm ITO transparent electrode. The spacer is a high temperature resistant adhesive tape, so just add it to complete the battery production. Platinum was sputtered on the conductive surface of the exposed transparent electrode. The completed battery was set on a hot plate and the whole temperature reached 80°C and then kept at 80°C. The germanium semiconductor was used as the working electrode and the transparent electrode was the counter electrode. The measurement was carried out at a potential sweep rate of 100mV/sec (Figure 9). The open voltage is 0.68V.

"Example 5"

In this embodiment, germanium is used as the semiconductor (first layer), and as the electrical The decomposition (second layer) uses vanadium(IV) sulphate oxide n water and an aqueous solution to produce thermoelectric power generation elements.

Dissolve 0.0570 g of vanadium oxide sulfate VOSO _{4 ‧nH 2} O (n=3~4) in 1M sulfuric acid aqueous solution, and degas the obtained 0.05M vanadium solution. After washing the ITO substrate (1.5×2.5cm) with platinum sputtered on the upper half of the area with sulfuric acid, paste the insulating tape with a diameter of 6mm on the remaining half, and drop 2.4μL into the hole. Vanadium aqueous solution. Cover the hole with a germanium wafer cleaned with sulfuric acid of the same size as the ITO substrate, keep it at 80°C, use germanium as the working electrode and the platinum side as the counter electrode, and perform CV measurement at a potential sweep speed of 100mV/sec (Figure 10). The open voltage is 0.23V.

"Example 6"

_{In this example, β-FeSi 2 was} used as the semiconductor (first layer) _{, RbCuCl 2 was} used as the electrolyte (second layer), and n-Si was used as the electron transport material (third layer) to fabricate a thermoelectric power generation element.

The 10×10×0.525mm n-Si was treated with hydrofluoric acid for 5 minutes. _{The β-FeSi 2} powder obtained by the SPS sintering method in the same procedure as in Example 1 was bonded to n-Si using silver paste, and dried at room temperature and 93° C. for 2 hours. The diameter of 10 mm [phi, a thickness of 15mm molded RbCuCl _2, disposed in the n-Si / β-FeSi ₂ assembly of the β-FeSi _2, pinched to slides, fixed insulating adhesive, for battery. A silver paste was applied to the n-Si side, _{platinum was sputtered on the RbCuCl 2} side as an electrode, and a platinum wire was used to connect the measuring device. The completed battery was set in an electric furnace and kept at 190°C, with n-Si as the working electrode and RbCuCl ₂ as the counter electrode, and the measurement was carried out at a potential sweep rate of 10 mV/sec (Figure 11). The open voltage is 0.25V.

〔Possibility of industrial use〕

The thermoelectric power generation element of the present invention and the thermoelectric power generation module containing it can be used for batteries, small portable power generation devices, geothermal power generation, thermoelectric power generation using the exhaust heat of automobiles, and use of substations, steel furnaces or garbage incineration plants The use of waste heat (emission heat) for thermoelectric power generation and other purposes.

Hereinafter, the present invention is described in a specific aspect, but the scope of the present invention also includes changes or improvements that are self-evident by those skilled in the art.

Claims (12)

A thermoelectric power generation element, a thermoelectric power generation element whose temperature gradient is not necessary, characterized by: a first layer containing a thermoelectric conversion material that generates thermally excited electrons and positive pores, and a solid electrolyte containing charge transport ion pairs that can move Or the second layer of the electrolyte solution is laminated, and the valence electron charge potential of the thermoelectric conversion material that generates thermally excited electrons and positive pores in the first layer is higher than that of the charge transport ion pair in the second layer. The potential is more positive, and at the interface between the first layer and the second layer, an oxidation reaction of the ions that are more likely to be oxidized among the aforementioned two ions occurs. If the temperature gradient of claim 1 is an optional thermoelectric power generation element, wherein the valence electron charged potential of the thermoelectric conversion material that generates thermally excited electrons and positive pores in the first layer is paired with the charge transport ion in the second layer The difference in oxidation-reduction potential is less than 0.5V. If the temperature gradient of claim 1 is a non-essential thermoelectric power generation element, the third layer containing the electron transport material is laminated on the side opposite to the laminated surface of the second layer of the first layer, the aforementioned third layer The electron conduction band potential of the electron transport material inside is the same as or positive as the conduction band potential of the thermoelectric conversion material that generates thermally excited electrons and positive pores in the first layer. If the temperature gradient of claim 3 is a non-essential thermoelectric power generation element, wherein the thermoelectric conversion in the first layer that generates thermionic and positive electric holes The difference between the conduction band potential of the material and the electron conduction band potential of the electron transport material in the third layer is 0.5V or less. If the temperature gradient of claim 1 is an unnecessary thermoelectric power generation element, wherein the thermoelectric conversion material that generates thermally excited electrons and positive holes in the first layer is the potential difference between the thermally excited electrons and the positive holes generated with them Thermoelectric conversion material above 0.1V. A method of power generation, characterized in that the thermoelectric power generation element of any one of Claims 1 to 5 is placed so that the thermoelectric conversion material that generates the thermally excited electrons and positive holes in the first layer has a thermally excited electron density of 10 ¹⁵ /m ³ in an environment above the temperature. The power generation method of claim 6, wherein the aforementioned temperature is a temperature at which the thermally excited electron density of the thermoelectric conversion material becomes 10 ¹⁸ /m ³ . A thermoelectric power generation device, characterized by including thermoelectric power generation elements in any one of Claims 1 to 5. A thermal battery, characterized by including thermoelectric power generation elements of any one of Claims 1 to 5. A thermoelectric power generation module, which is characterized by including a thermoelectric power generation element of any one of Claims 1 to 5. A method of thermoelectric power generation, characterized by comprising the steps of arranging the thermoelectric power generation module of claim 10 in a place where heat is generated, and the step of heating the thermoelectric power generation module by heat to generate electricity. Such as the thermoelectric power generation method of claim 11, wherein the aforementioned heat is geothermal or exhaust heat.

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