KR20130024686A - HIGHLY EFFICIENT π-TYPE THERMOELECTRIC MODULE FOR POWER GENERATION AND PREPARING METHOD OF THE SAME - Google Patents

Abstract

PURPOSE: A highly efficient π-type thermoelectric module for power generation and a method for fabricating the same are provided to improve the adhesion of a substrate and an electrode by using metal gauze and metal paste. CONSTITUTION: A lower electrode(124) is formed on a lower plate(150). An upper electrode(122) is formed on an upper plate(110). A P-n thermal thermoelectric material(130,140) is formed between the upper electrode and the lower electrode. The p-n thermoelectric material includes a pillar p-type thermoelectric material and an n-type thermoelectric material. The P-n thermoelectric material has a rectangular shape.

Description

High-efficiency π-type thermoelectric module for power generation and its manufacturing method {HIGHLY EFFICIENT π-TYPE THERMOELECTRIC MODULE FOR POWER GENERATION AND PREPARING METHOD OF THE SAME}

The present application provides a high efficiency π for power generation comprising a p-type Ca _{3 - x} Cu _x Co ₄ O ₉ (0≤x≤3) thermoelectric material and an n-type Ca _{1 - y} Dy _y MnO ₃ (0≤y≤1) thermoelectric material It relates to a type thermoelectric module, and a method of manufacturing the same.

Thermoelectric material is a generic term for materials that use various effects of heat and electricity interactions.Thermistors are used to stabilize circuits, detect heat, power, light, and the Seebeck effect. The material used, the material using the Peltier effect used for a refrigerator or a thermostat, etc. are mentioned.

In particular, as the environmental pollution problem and the energy depletion problem caused by the use of fossil fuels have become serious all over the world, researches are actively conducted to create alternative energy for materials using the Seebeck effect, a phenomenon in which electromotive force is generated due to temperature difference. It is becoming. In the thermoelectric module for power generation using thermoelectric materials, electrons and holes are moved from the high end to the low end in the n-type thermoelectric material and the p-type thermoelectric material, respectively, when the heat is transferred from the hot end region to the cold end region due to the temperature difference at both ends. By moving, electrical energy is generated.

In addition, the efficiency of the π-type thermoelectric module for power generation is determined by thermoelectric characteristics such as thermoelectric power, thermal conductivity and electrical resistivity of p-type and n-type thermoelectric materials and the number of pairs of thermoelectric modules. Thermoelectric power generation with no noise, no vibration, no maintenance, and high reliability, was initially developed for application to special small power supplies, including military power supplies. There are various types of heat sources available from sources to high heat sources, such as 1,000 ℃, and their use is expanding to fields such as thermoelectric generators using industrial waste heat and alternative independent power sources.

Korean Unexamined Patent Application Publication No. 10-2010-0116748 discloses a thermoelectric module formed using a p-type semiconductor and an n-type semiconductor formed by plasma arc discharge. In addition, Korean Patent No. 10-0853749 discloses a thermoelectric power unit module in which two pairs of p-type thermoelectric material and n-type thermoelectric material are manufactured in series, and by using a thermoelectric set in which a plurality of the unit modules are connected in series, for each module. Disclosed are a thermoelectric power unit module, a thermoelectric set including the same, and a method of manufacturing the same, which make it easy to check a resistance value and disconnection, and easily analyze and solve a cause of a failure, and easily connect a large number of modules. .

However, development of a manufacturing process of the thermoelectric module is still required to improve the output characteristics of the thermoelectric module.

The present application provides a high efficiency π for power generation comprising a p-type Ca _{3 - x} Cu _x Co ₄ O ₉ (0≤x≤3) thermoelectric material and an n-type Ca _{1 - y} Dy _y MnO ₃ (0≤y≤1) thermoelectric material To provide a thermoelectric module, and a method of manufacturing the same.

However, the problems to be solved by the present invention are not limited to the above-mentioned problems, and other problems not mentioned can be clearly understood by those skilled in the art from the following description.

The first aspect of the present application, the lower electrode formed on the lower substrate and the upper electrode formed on the upper substrate; And a plurality of pn thermoelectric materials including a plurality of pn thermoelectric materials in a shape in which columnar p-type thermoelectric materials and columnar n-type thermoelectric materials are alternately disposed between the upper electrode and the lower electrode. A thermoelectric module, wherein the p-type thermoelectric material includes Ca _{3 - x} Cu _x Co ₄ O ₉ (0≤x≤3) thermoelectric material, and the n-type thermoelectric material is Ca _{1 -y} Dy _y MnO ₃ (0 ≦ y≤1) It is possible to provide a π-type thermoelectric module for power generation including a thermoelectric material.

A second aspect of the present application can provide a method of manufacturing a π-type thermoelectric module for power generation, including:

p-type thermoelectric with columnar shape by sintering p-type Ca _{3 - x} Cu _x Co ₄ O ₉ (0≤x≤3) thermoelectric material and n-type Ca _{1 - y} Dy _y MnO ₃ (0≤y≤1) Manufacturing a material and a columnar n-type thermoelectric material;

Forming a lower electrode on the lower substrate;

Forming an upper electrode on one surface of each of the p-type thermoelectric material and the n-type thermoelectric material;

The p-type thermoelectric material and the column-shaped n-type thermoelectric material are adhered to each other by adhering opposite surfaces of one surface on which the upper electrode of the p-type thermoelectric material and the n-type thermoelectric material are formed to the lower electrode, respectively. Alternately arranging to form a plurality of π-type thermoelectric modules; And

Adhering an upper substrate on the upper electrode.

By the present application, for power generation comprising p-type Ca _{3 - x} Cu _x Co ₄ O ₉ (0≤x≤3) thermoelectric material and n-type Ca _{1 - y} Dy _y MnO ₃ (0≤y≤1) thermoelectric material A high efficiency [pi] type thermoelectric module and a manufacturing method thereof are provided. Specifically, the adhesion between the electrode and the substrate may be improved by using a metal paste and / or metal gauze when forming the electrode, thereby improving output characteristics of the π-type thermoelectric module.

Figure 1a is a cross-sectional view showing the internal configuration of the π-type thermoelectric module according to an embodiment of the present application.
Figure 1b is a top view of the π-type thermoelectric module according to an embodiment of the present application.
2A to 2E are views for explaining a method of manufacturing a π-type thermoelectric module for power generation according to an embodiment of the present application.
Figure 3 is a picture showing a π-type Ca _2.76 Cu _0.24 Co ₄ O ₉ / Ca _0.8 Dy _0.2 MnO ₃ thermoelectric module for high efficiency power generation according to an embodiment of the present application.
FIG. 4 is a photograph showing π-type (a) two-pair thermoelectric module and (b) four-pair thermoelectric module having an (Ag paste + Ag gauze) electrode according to an embodiment of the present disclosure.
5 is a photograph showing an output characteristic measuring apparatus of a π-type thermoelectric module according to an exemplary embodiment of the present application.
Figure 6 is a graph showing the electrical conductivity of the (Ag paste + Ag gauze) mixture electrode according to an embodiment of the present application.
7 is a view showing a p-type _{Ca 2 .76 Cu 0 .24 Co 4} O 9 thermoelectric material and Ag electrode interface according to one embodiment of the present application.
8 is n-type in accordance with one embodiment of the present Ca _{0 .8} Dy _{0 .2} MnO ₃ A diagram showing an interface between a thermoelectric material and an Ag electrode.
9 is a graph illustrating output characteristics of a π-type unit thermoelectric module having an Ag paste electrode according to an exemplary embodiment of the present disclosure.
FIG. 10 is a graph illustrating output characteristics of a π-type unit thermoelectric module having an (Ag paste + Ag gauze) electrode according to an exemplary embodiment of the present disclosure.
FIG. 11 is a graph illustrating output characteristics of a π-type unit thermoelectric module having a temperature difference when a temperature of a high temperature part is 380 ° C. according to an embodiment of the present disclosure.
FIG. 12 is a graph illustrating output characteristics of a π-type unit thermoelectric module having a temperature difference when a temperature of a high temperature part is 530 ° C. according to an embodiment of the present disclosure.
13 is a graph illustrating a temperature difference of a π-type unit thermoelectric module according to a temperature of a high temperature part according to an exemplary embodiment of the present application.
14 is a graph illustrating output characteristics of a π-type unit thermoelectric module when the temperature of the high temperature part is 380 ° C. according to an embodiment of the present disclosure.
15 is a graph illustrating output characteristics of a π-type unit thermoelectric module when the temperature of the high temperature part is 510 ° C. according to an embodiment of the present disclosure.
16 is a graph illustrating output characteristics of a π-type unit thermoelectric module when the temperature of the high temperature part is 550 ° C. according to an embodiment of the present disclosure.
17 is a graph illustrating output characteristics of a π-type unit thermoelectric module when the temperature of the high temperature part is 611 ° C. according to an embodiment of the present disclosure.
18 is a graph illustrating output characteristics of a π-type unit thermoelectric module when the temperature of the high temperature part is 672 ° C. according to an embodiment of the present disclosure.
19 is a graph illustrating output characteristics of a π-type unit thermoelectric module when the temperature of the high temperature part is 713 ° C. according to an embodiment of the present disclosure.
20 is a graph showing the output characteristics of the π-type two-pair thermoelectric module when the temperature of the high temperature unit according to an embodiment of the present application is 600 ℃.
21 is a graph illustrating output characteristics of a π-type four-pair thermoelectric module when the temperature of the high temperature part is 664 ° C. according to an embodiment of the present disclosure.
FIG. 22 is a graph illustrating output characteristics of π-type 1 pair, 2 pair, and 4 pair thermoelectric modules for each temperature of a high temperature part according to an exemplary embodiment of the present disclosure.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. It should be understood, however, that the present invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In the drawings, the same reference numbers are used throughout the specification to refer to the same or like parts.

Throughout this specification, when a part is referred to as being "connected" to another part, it is not limited to a case where it is "directly connected" but also includes the case where it is "electrically connected" do.

Throughout this specification, when a member is located "on" another member, this includes not only when one member is in contact with another member but also when another member exists between the two members.

Throughout this specification, when an element is referred to as "including " an element, it is understood that the element may include other elements as well, without departing from the other elements unless specifically stated otherwise. The terms "about "," substantially ", etc. used to the extent that they are used throughout the specification are intended to be taken to mean the approximation of the manufacturing and material tolerances inherent in the stated sense, Accurate or absolute numbers are used to help prevent unauthorized exploitation by unauthorized intruders of the referenced disclosure. The word " step (or step) "or" step "used to the extent that it is used throughout the specification does not mean" step for.

Throughout this specification, the term “combination of these” included in the expression of the mark of the form refers to one or more mixtures or combinations selected from the group consisting of the elements described in the mark of the form of Markus, wherein the components It means to include one or more selected from the group consisting of.

Hereinafter, exemplary embodiments will be described in detail with reference to the accompanying drawings. However, it is not limited to these embodiments and examples herein.

The first aspect of the present application, the lower electrode formed on the lower substrate and the upper electrode formed on the upper substrate; And a plurality of pn thermoelectric materials comprising a plurality of pn thermoelectric materials in a shape of alternately arranged columnar p-type thermoelectric materials and columnar n-type thermoelectric materials between the upper electrode and the lower electrode. A thermoelectric module, wherein the p-type thermoelectric material includes Ca _{3 - x} Cu _x Co ₄ O ₉ (0≤x≤3) thermoelectric material, and the n-type thermoelectric material is Ca _{1 -y} Dy _y MnO ₃ (0 ≦ y≤1) It is possible to provide a π type thermoelectric module for generating power, including a thermoelectric material.

According to the exemplary embodiment of the present application, the plurality of p-n thermoelectric materials may be formed in a square shape, but is not limited thereto. For example, the plurality of p-n thermoelectric materials may be alternately arranged in one direction, alternately arranged in a direction perpendicular to the one direction, or three-dimensional alternatingly.

According to the exemplary embodiment of the present application, the plurality of pn thermoelectric materials may be in a square shape including one to four p-type thermoelectric materials and one to four n-type thermoelectric materials that are alternately arranged. However, it is not limited thereto.

According to the exemplary embodiment of the present application, the p-type thermoelectric material and the n-type thermoelectric material may be in the form of a module connected in a π type such that they are electrically connected in series and thermally in parallel, but is not limited thereto.

A second aspect of the present application can provide a method of manufacturing a π-type thermoelectric module for power generation, including:

p type Ca _{3 - x} Cu _x Co ₄ O ₉ (0≤x≤3) thermoelectric material and n type Ca _{1 - y} Dy _y MnO ₃ (0≤y≤1) thermoelectric material Manufacturing a material and a columnar n-type thermoelectric material;

Forming a lower electrode on the lower substrate;

Forming an upper electrode on one surface of each of the p-type thermoelectric material and the n-type thermoelectric material;

The p-type thermoelectric material and the column-shaped n-type thermoelectric material are adhered to each other by adhering opposite surfaces of one surface on which the upper electrode of the p-type thermoelectric material and the n-type thermoelectric material are formed to the lower electrode, respectively. Alternately arranged to form a plurality of π-type thermoelectric modules; And

Adhering an upper substrate on the upper electrode.

According to the exemplary embodiment of the present disclosure, the method may further include bonding the upper substrate and the lower substrate using two or more of the π-type thermoelectric module for power generation, but is not limited thereto.

According to the exemplary embodiment of the present application, the sintering temperature of the p-type thermoelectric material may be about 800 ° C. to about 1,000 ° C., but is not limited thereto.

According to one embodiment of the present application, the sintering temperature of the n-type thermoelectric material may be about 1,100 ℃ to about 1,300 ℃, but is not limited thereto.

According to the exemplary embodiment of the present application, the manufacturing method may further include heat treatment at about 500 ° C. to about 1,000 ° C. after pressurizing the π-type thermoelectric module, but is not limited thereto.

According to one embodiment of the present application, the upper electrode and the lower electrode may be formed by sintering a paste containing a metal powder, respectively, but is not limited thereto.

According to one embodiment of the present application, the metal powder may include a metal selected from the group consisting of Au, Ag, Pd, Ni, Cu, and combinations thereof, but is not limited thereto.

According to the exemplary embodiment of the present application, each of the upper electrode and the lower electrode may include a paste layer containing the metal powder, a metal gauze, and the paste layer containing the metal powder on the upper substrate and the lower substrate. By sequentially stacking, the upper substrate and the lower substrate may be bonded to each other, but are not limited thereto.

According to one embodiment of the present application, the metal gauze may include, but is not limited to, a metal selected from the group consisting of Au, Ag, Pd, Ni, Cu, and combinations thereof.

According to one embodiment of the present application, the upper electrode and the lower electrode may be formed using a screen printing process, but is not limited thereto.

Figure 1a is a cross-sectional view showing the internal configuration of the π-type thermoelectric module according to an embodiment of the present application, Figure 1b is a top view of the π-type thermoelectric module according to an embodiment of the present application.

As illustrated in FIGS. 1A and 1B, the π-type thermoelectric module 100 according to the exemplary embodiment of the present disclosure may have upper and lower surfaces formed by the upper substrate 110 and the lower substrate 150. For insulating the upper and lower portions of the π-type thermoelectric module 100, the upper substrate 110 and the lower substrate 150 may be, for example, an alumina (Al ₂ O ₃ ) insulating substrate. It is not limited.

An electrode 120 may be provided on a lower surface of the upper substrate 110 and an upper surface of the lower substrate 150. The electrode 120 guides the flow of power in the π-type thermoelectric module 100. The electrode 120 contacts the lower surface of the upper substrate 110 and the upper surface of the lower substrate 150. The lower electrode 124 may be included.

The upper electrode 122 and the lower electrode 124 are preferably made of a material having high electrical conductivity such that a large amount of current flows in the π-type thermoelectric module 100. Specifically, the upper electrode 122 and the lower electrode 124 may be formed by sintering a paste containing a metal powder, respectively. In more detail, the metal powder may be formed of a material having excellent conductivity, including, for example, selected from the group consisting of Au, Ag, Pd, Ni, Cu, and combinations thereof. In one embodiment, the upper electrode 122 and the lower electrode 124, each of the paste layer containing the metal powder on the upper substrate 110 and the lower substrate 150, The metal gauze and the paste layer containing the metal powder may be sequentially laminated to be bonded to each of the lower substrate and the upper substrate.

On one surface of the upper electrode 122 and the lower electrode 124, a columnar p-type thermoelectric material 130 and a columnar n-type thermoelectric material 140 that face each other are alternately arranged to form a plurality of π-type thermoelectrics. Modules may be provided. In more detail, a p-type thermoelectric material 130 is provided on a lower right side of the upper electrode 122, and an n-type thermoelectric material 140 is provided at a position spaced to the left from the p-type thermoelectric material 130. do. In addition, an n-type thermoelectric material 140 is provided on the upper left side of the lower electrode 124, and a p-type thermoelectric material 130 is provided at a position spaced to the right from the n-type thermoelectric material 140. Accordingly, the upper substrate 110 and the lower substrate 150 are connected to each other to allow the p-type thermoelectric material 130 and the n-type thermoelectric material 140 to be electrically in series. By the series connection of the p-type thermoelectric material 130 and the n-type thermoelectric material 140, the plurality of p-type thermoelectric material 130 and the n-type thermoelectric material 140 couple together to form one electric energy path. Thus, the plurality of pn thermoelectric materials may have a rectangular shape. The plurality of pn thermoelectric materials 140 and 150 may be formed in a columnar shape, and may be formed in a rectangular columnar shape in view of ease of processing, but are not limited thereto. In this case, an oxide may be used as the p-type thermoelectric material 130 and the n-type thermoelectric material 140. In the case of oxide materials, the continuous use of R & D has expanded the temperature range, and it is more environmentally friendly than non-oxide materials, can be used for a long time in the air, and is easy to lighten and downsize. In one embodiment of the present application, the p-type thermoelectric material 130, Ca _{3 - x} Cu _x Co ₄ O ₉ (0≤x≤3) thermoelectric material, the n-type thermoelectric material 140, Ca _{1 - y} Dy _y MnO ₃ (0 ≦ _y ≦ 1) thermoelectric material may be used. The thermoelectric material has an excellent output factor value that is a measure of the performance of the thermoelectric material.

Next, the manufacturing method of the p type thermoelectric module for power generation which concerns on this application is demonstrated.

2A to 2E are views for explaining a method of manufacturing a π-type thermoelectric module for power generation according to an embodiment of the present application. With reference to Figures 2a to 2e will be described a method of manufacturing a π-type thermoelectric module for power generation according to an embodiment of the present application.

First, as shown in FIG. 2A, the thermoelectric material of the p-type thermoelectric material 130 is Ca _{3 -x} Cu _x Co ₄ O ₉ (0 ≦ _x ≦ 3), and the thermoelectric material of the n-type thermoelectric material 140. _{Ca 1 - y Dy y MnO 3} (0≤y≤1) , each of the composite powder to produce a p-type thermoelectric material 130 and the n-type thermoelectric material 140.

The thermoelectric material has a large power factor value. That is, the thermoelectric conversion performance is good. Therefore, it can be usefully used in thermoelectric conversion materials in place of or in addition to conventional thermoelectric conversion materials.

The synthesized p-type thermoelectric material powder and the n-type thermoelectric material powder may be in a powder state having a size of about 150 nm or less, but is not limited thereto. The p-type thermoelectric material powder and the n-type thermoelectric material powder may be put into a mold (not shown) prepared in advance, and then pressurized to produce a molded body, and then sintered. In the sintering process, an atmospheric atmosphere and a temperature at which oxide thermoelectric powder is sintered, for example, the p-type thermoelectric material 130 may be sintered at a temperature of about 900 ° C., and the n-type thermoelectric material 140 may be about 1,200. It may be formed by sintering at ℃. The p-type thermoelectric material 130 and the n-type thermoelectric material 140 pellets prepared by the sintering process have a width and length of about 3 mm to about 15 mm, and a height of about 20 mm to about 30 mm. Phosphorus may be formed in a pillar shape, in terms of ease of processing may be formed in a square pillar shape, but the size and shape is not limited.

Subsequently, as shown in FIG. 2B, the lower electrode 124 may be formed on the lower substrate 150. The upper substrate 110 and the lower substrate 150 may use an alumina (Al ₂ O ₃ ) insulating substrate to insulate the upper and lower portions of the π-type thermoelectric module 100, but is not limited thereto.

In one embodiment, the lower electrode 124 may be formed by depositing a metal mask (not shown) or a metal mash (not shown), which is prepared in advance, and then a metal such as ball milled silver or copper. The electrode 120 may be formed by passing the powder through a metal mask or a metal mesh.

That is, fine holes are formed in the metal mask or metal mesh at the position where the electrode 120 is to be formed, and the metal powder such as silver or copper passes through the micro holes to pass on the lower substrate 150. The lower electrode 124 can be screen printed on.

Subsequently, as shown in FIG. 2C, in the thermoelectric material arrangement step in which the upper electrode 122 or the lower electrode 124 is formed, the p-type thermoelectric material 130 and the n-type thermoelectric material 140 are alternately arranged in one direction. By arranging a plurality of thermoelectric materials that are alternately arranged in the direction perpendicular to the one direction, a plurality of π-type unit modules using a pair of p-type thermoelectric material 130 and n-type thermoelectric material 140 as π-type unit modules It may be provided, and can be arranged side by side with each other. The plurality of p-n thermoelectric materials may have a rectangular shape.

Subsequently, as illustrated in FIG. 2D, an upper electrode 122 may be formed on one surface of each of the p-type thermoelectric material 130 and the n-type thermoelectric material 140. Since the upper electrode 122 may be formed in the same manner as the lower electrode 124, a redundant substrate is omitted.

Subsequently, as illustrated in FIG. 2E, the upper substrate 110 may be bonded onto the upper electrode 122. In one embodiment, the π-type thermoelectric module 100 may be formed by applying heat to the upper substrate 110 while applying pressure to the upper electrode 122.

Hereinafter, the present invention will be described in detail with reference to embodiments and drawings. However, the present invention is not limited to these embodiments and drawings.

1. Experimental method

1) Fabrication of π type thermoelectric module

A) Fabrication of π type unit thermoelectric module

By using the n-type Ca _{0 .8} Dy _{0 .2} MnO ₃ thermoelectric material sintered at 900 ℃ _.24 a p-type _{Ca 2 .76 Cu 0 Co 4 O} 9 and sintered at 1,250 ℃ prepare a π-type thermoelectric module. Cutting the manufacture of p-type _{Ca 2 .76 Cu 0 .24 Co 4} O 9 and the n-type Ca _{0 .8} Dy _{0 .2} MnO ₃ thermoelectric material was then machined to a size of approximately 7 mm x 9 mm x 25 mm . In this embodiment, in order to compare the output characteristics of the unit thermoelectric module according to the type of electrode, a thermoelectric module using only Ag paste as an electrode and a thermoelectric module using a mixture of (Ag paste + Ag gauze) as electrodes were manufactured. At this time, an alumina substrate having a size of 20 mm x 20 mm having a thickness of 4 mm was used.

First, in the case of a thermoelectric module having an Ag paste electrode, Ag paste was printed on one side of the alumina substrate, and then Ag paste was printed on one side of the p-type and n-type thermoelectric materials, respectively. Then, after bonding the alumina substrate and the two thermoelectric materials, a thermoelectric module was prepared by heat treatment at 700 ℃ for 1 hour while applying a pressure of 12.3 kPa. In the case of a thermoelectric module having an (Ag paste + Ag gauze) electrode, Ag paste was printed on an alumina substrate, and then Ag Ag gauze (80 mesh) having a thickness of 0.1 mm was attached thereon, and Ag paste was coated on Ag gauze. Ag pastes permeated between the gauze to ensure good adhesion to each other. Ag pastes were printed on one side of the p-type and n-type thermoelectric materials, respectively. Subsequently, the substrate to which the Ag electrode was attached and the p-type / n-type thermoelectric material were bonded with Ag paste, and then heat-treated at 700 ° C. for 1 hour while applying a pressure of 12.3 kPa as in the thermoelectric module prepared above. 3 shows a photo of a p-type unit thermoelectric module having two different electrodes.

B) Fabrication of π-type 2-pair and 4-pair thermoelectric modules

To obtain higher output characteristics, π-type 2-pair and 4-pair thermoelectric modules were fabricated. Of the two types of unit thermoelectric modules manufactured above, the output characteristics of the unit thermoelectric module having the (Ag paste + Ag gauze) electrode are better, so in this embodiment, two pairs and four having the (Ag paste + Ag gauze) electrode A double thermoelectric module was produced. Two pairs of thermoelectric modules were manufactured by connecting π-type unit thermoelectric modules in series, and two pairs of thermoelectric modules were manufactured, and then four pairs of thermoelectric modules were manufactured by connecting these two thermoelectric modules in series with (Ag paste + Ag gauze). It was. The π-type 2-pair and 4-pair thermoelectric modules thus produced are shown in FIG. 4.

2) Analysis of junction characteristics of thermoelectric materials and electrodes

A) Characteristics of the electrode

In order to manufacture π-type thermoelectric module for high temperature, an electrode having high conductivity and stability at high temperature is required. High temperature conductive electrodes are generally used as a paste by mixing metal powders such as Au, Ag, Pd, Ni, Cu, inorganic binders and organic binders. Among them, Ag paste is more economical than Au paste and is widely used because of its high conductivity even at high temperatures. Therefore, in the present embodiment, a mixture of (Ag paste + Ag gauze) was used as an electrode, and high temperature electrical conductivity of the electrode was measured at 100 ° C. to 800 ° C. by a four-terminal method.

B) Element distribution at the interface of thermoelectric material and electrode

Element diffusion at the junction between the p-type / n-type thermoelectric material and the electrode has a great influence on the output characteristics and the bonding strength of the thermoelectric module. After bonding, p-type Ca _{2 .76} Cu _{0. Of} a thermoelectric module heat-treated at 700 ° C. for 1 hour while applying a pressure of 12.3 kPa to investigate the diffusion of Ag into the thermoelectric material and the diffusion of constituent elements of the thermoelectric material with the Ag electrode _{. 24} Co ₄ O ₉ / electrode was the interface between the n-type Ca _{0 .8 .2 0} Dy EDS analysis in the MnO ₃ / electrode interface.

3) Measurement of output characteristics of manufactured π type thermoelectric module

In order to improve the output characteristics of the manufactured π-type thermoelectric module, the heating heater and the coolant moving square pipe are brought into contact with the thermoelectric module to greatly increase the temperature difference (T = T _h -T _c ) between the high temperature part (T _h ) and the low temperature part (T _c ). It was. The heater used a nichrome wire heating element, and connected the lake to the coolant moving square pipe to flow the coolant. In addition, K-type thermocouples were installed on the alumina substrate and the low temperature alumina substrate bonded to the p-type and n-type thermoelectric materials to measure the temperature of the hot and cold portions of the thermoelectric module. Next, Ag gauze was attached to the low temperature portions of the n-type and p-type thermoelectric materials in order to measure the current and voltage generated when there is a temperature difference at both ends of the thermoelectric module, and then the Ag gauze and the copper wire were connected. 5 shows a thermoelectric module and a device prepared for measuring output characteristics. A microcurrent was flowed through the thermoelectric module using a constant current supply (Keithley 2400), and the electromotive force generated at this time was measured by a digital multimeter (Fluke 87-3) to calculate the output of the thermoelectric module.

2. Results and discussion

1) Bonding Characteristics of Thermoelectric Materials and Electrodes

Figure 6 shows the electrical conductivity of the (Ag paste + Ag gauze) mixture electrode in the range of 100 ℃ ~ 800 ℃. The electrical conductivity of the Ag electrode decreased with increasing temperature, and the electrical conductivity was 3.84 × 10 ⁴ Ω ^-1 cm ^{- 1} and 1.69 × 10 ⁴ Ω ^-1 cm ^-1 at 100 ℃ and 800 ℃, respectively.

Figure 7 is a photograph of the p-type _{.24 Ca 2 .76 Cu 0 Co 4 O} 9 thermoelectric material with Ag electrode. As shown in FIG. 7, the thickness of the attached Ag electrode is approximately 20 μm. Although Ag is not substantially diffuse into the thermoelectric material, Ca ₂ Cu _{.76 0 .24} Co ₄ O configuration element of Ca, Cu, Co, O and ₉ was a small amount of the Ag diffusion into the electrode, among these elements is Cu The most spread. Figure 8 is an n-type Ca _{0 .8} Dy _{0 .2} MnO ₃ Photo shows the thermoelectric material and the Ag electrode, and the thickness of the attached Ag electrode is approximately 27 μm. a p-type Ca ₂ Cu _{0 .76 .24} Like Co ₄ O ₉ Ag did not substantially diffuse into the thermoelectric material, Ca _{0 .8} Dy _{0 .2} MnO ₃ in the constituent elements Ca, Dy, Mn, Ag and O, A small amount diffused into the electrode.

2) Output characteristics of π-type unit thermoelectric module having two different electrode types

A) π-type unit thermoelectric module with Ag paste electrode

The output characteristics of the unit thermoelectric module having the Ag paste electrode in the state without flowing the cooling water were measured. When the temperature of the high temperature portion was 395 ° C, the temperature of the low temperature portion was 177 ° C, the temperature difference was 218 ° C, and the open circuit electromotive force was 52.3 mV at this temperature difference. Next, the voltage (V) and the current (I) generated when a microcurrent in the range of 0 mA to 200 mA were applied to the thermoelectric module were measured, and the power (W) was calculated using the result. 7 shows the relationship between VI and WI of the unit thermoelectric module. In Figure 9 it can be seen that the value of the maximum output is 2.41 mW.

B) π-type unit thermoelectric module with (Ag paste + Ag gauze) electrode

Similarly to the unit thermoelectric module using the Ag paste as an electrode, the output characteristics of the π-type unit thermoelectric module having a mixture electrode (Ag paste + Ag gauze) when the temperature of the high temperature portion was 392 ° C. without cooling water was obtained. Here, the temperature difference between the hot and cold parts was 230 ° C, which was 12 ° C greater than the thermoelectric module measured above, but the open circuit electromotive force was about 52.2 mV. (Ag paste + Ag gauze) The voltage and current generated while flowing a microcurrent in the range of 0 mA to 200 mA to a π-type unit thermoelectric module having an electrode were measured. The relationship is shown. The maximum output value was 2.81 mW.

C) Comparison of output characteristics of π-type unit thermoelectric module with two different Ag electrodes

In order to compare the output characteristics of the unit thermoelectric module according to the electrode type, Table 1 summarizes the temperature difference, the open circuit electromotive force, and the output of the π-type unit thermoelectric module having an Ag paste electrode and an (Ag paste + Ag gauze) electrode. In this embodiment, π-type 2-pair and 4-pair thermoelectric modules were fabricated using (Ag paste + Ag gauze) electrodes with better output characteristics. After that, the output characteristics of the high temperature section, the temperature difference and the number of thermoelectric module pairs were studied.

3) Output characteristics of π-type unit thermoelectric module according to the temperature of high temperature part

The effect of temperature difference on the output characteristics was investigated by fixing the temperature of the hot part at 380 ° C and adjusting the flow rate. Before the cooling water flowed, the temperature difference was 190 ° C, but by flowing the cooling water, the temperature difference greatly increased to 265 ° C. Voltage and current were measured under these two temperature differences, and the output values calculated using the same are shown in FIG. 11. When the temperature difference was 190 ° C, the values of the open circuit electromotive force and the maximum output were 31.4 mV and 1.25 mW, respectively. Also, when the temperature difference was 265 ° C, the values of the open circuit electromotive force and the maximum output were 43.8 mV and 2.42 mW, respectively.

In addition, the output characteristics are shown in FIG. 12 when the temperature of the high temperature part is 530 ° C and the temperature difference is 215 ° C and 260 ° C. When the temperature difference is 215 ℃, the open circuit electromotive force and the maximum output are 41.4 mV and 2.39 mW, respectively, and when the temperature difference is 260 ℃, the open circuit electromotive force and the maximum output are 50.1 mV and 3.75 mW. From these results, it can be seen that the output increases significantly as the temperature difference is large.

13 is a graph showing a temperature difference generated by flowing cooling water when the temperature of the high temperature part is 250 ° C to 720 ° C. As the temperature of the hot portion increased, the temperature difference increased almost linearly. When the temperature of the hot portion increased to 380 ° C, 510 ° C, 550 ° C, 611 ° C, 672 ° C, and 713 ° C, the temperature difference was 250 ° C, 269 ° C, 293 ° C, respectively. 305 ° C, 324 ° C, and 346 ° C. The temperature difference, the open circuit electromotive force, and the output at the temperatures of the various high temperature parts are shown in Table 2, and the relationship between V-I and W-I of the p-type unit thermoelectric module for each temperature of the high temperature part is shown in FIGS. 14 to 19, respectively. When the temperature of the hot portion is 380 ° C, 510 ° C, 550 ° C, 611 ° C, 672 ° C, and 713 ° C, the values of the maximum output are 2.42 mW, 3.65 mW, 4.26 mW, 5.70 mW, 7.13 mW, and 8.42 mW, respectively. As the temperature of the hot portion increases, the output increases.

4) Output Characteristics of π-type 2 Pair Thermoelectric Module

In order to obtain large electromotive force, it is necessary to connect several pairs of thermoelectric modules in series. In this embodiment, two pairs and four pairs of π-type thermoelectric modules were manufactured to evaluate output characteristics. 20 is a graph showing VI and WI characteristics of a p-type two-pair thermoelectric module when the temperature of the high temperature part is 600 ° C. and the temperature difference is 317 ° C. FIG. Under these conditions, the open circuit electromotive force and maximum output value were 134 mV and 15.33 mW, respectively. This output is about 2.7 times higher than the output of the unit thermoelectric module (5.7 mW), which was obtained when the temperature of the hot part was 611 ° C. The more than twice the output is considered to be because the temperature difference (317 ° C) is greater than the temperature difference (305 ° C) when measuring the output of the unit thermoelectric module when measuring the output of the two pairs of thermoelectric modules.

5) Output Characteristics of π-Type 4 Pair Thermoelectric Module

21 shows the relationship between VI and WI of the π-type 4-pair thermoelectric module when the temperature of the high temperature part is 664 ° C and the temperature difference is 321 ° C. The measured open circuit electromotive force and maximum output value were 282 mV and 31.12 mW, respectively. 22 shows the output characteristics of the π-type unit thermoelectric module, the two pair thermoelectric module, and the four pair thermoelectric module according to the temperature of the high temperature section.

It will be understood by those of ordinary skill in the art that the foregoing description of the embodiments is for illustrative purposes and that those skilled in the art can easily modify the invention without departing from the spirit or essential characteristics thereof. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive. For example, each component described as a single entity may be distributed and implemented, and components described as being distributed may also be implemented in a combined form.

The scope of the present application is indicated by the following claims rather than the above description, and it should be construed that all changes or modifications derived from the meaning and scope of the claims and their equivalents are included in the scope of the present application.

100: thermoelectric module
110: upper substrate
120: electrode
122: upper electrode
124: lower electrode
130: p-type thermoelectric material
140: n-type thermoelectric material
150: lower substrate

Claims (12)

A lower electrode formed on the lower substrate and an upper electrode formed on the upper substrate; And
A plurality of pn thermoelectric materials forming a shape in which columnar p-type thermoelectric materials and columnar n-type thermoelectric materials that face each other are alternately arranged between the upper electrode and the lower electrode.
As a π-type thermoelectric module for power generation, including
The p-type thermoelectric material includes Ca _{3 - x} Cu _x Co ₄ O ₉ (0≤x≤3) thermoelectric material, and the n-type thermoelectric material is Ca _{1 - y} Dy _y MnO ₃ (0≤y≤1) Including a thermoelectric material,
Π type thermoelectric module for power generation.
The method of claim 1,
The plurality of pn thermoelectric material is a square shape, π type thermoelectric module for power generation.
The method of claim 1,
The plurality of pn thermoelectric material to form a square shape, including one to four of the p-type thermoelectric material and one to four n-type thermoelectric material are alternately arranged, π type thermoelectric module for power generation.
p-type Ca _3-x Cu _x Co ₄ O ₉ (0≤x≤3) thermoelectric material and n-type Ca _1-y Dy _y MnO ₃ (0≤y≤1) thermoelectric material Manufacturing a thermoelectric material and a columnar n-type thermoelectric material;
Forming a lower electrode on the lower substrate;
Forming an upper electrode on one surface of each of the p-type thermoelectric material and the n-type thermoelectric material;
The p-type thermoelectric material and the p-type thermoelectric material and the column-shaped n-type thermoelectric material are bonded to each other by attaching opposite surfaces of one surface on which the upper electrode of the n-type thermoelectric material is formed to the lower electrode. Forming a plurality of π-type thermoelectric modules having a shape of alternately arranged ones; And
Adhering an upper substrate on the upper electrode
Including, the manufacturing method of π-type thermoelectric module for power generation.
The method of claim 4, wherein
And bonding the upper substrate and the lower substrate using two or more of the π-type thermoelectric modules for power generation.
The method of claim 4, wherein
The sintering temperature of the p-type thermoelectric material is 800 ℃ to 1,000 ℃, the manufacturing method of π-type thermoelectric module for power generation.
The method of claim 4, wherein
The sintering temperature of the n-type thermoelectric material is 1,100 ℃ to 1,300 ℃, the manufacturing method of π-type thermoelectric module for power generation.
The method of claim 4, wherein
After the pressurizing the π-type thermoelectric module further comprises a heat treatment at 500 ℃ to 1,000 ℃, manufacturing method of the π-type thermoelectric module for power generation.
The method of claim 4, wherein
And the upper electrode and the lower electrode are each formed by sintering a paste containing metal powder.
The method of claim 9,
The metal powder comprises a metal selected from the group consisting of Au, Ag, Pd, Ni, Cu, and combinations thereof.
The method of claim 4, wherein
Each of the upper electrode and the lower electrode is formed by sequentially laminating a paste layer containing the metal powder, a metal gauze, and a paste layer containing the metal powder on the upper substrate and the lower substrate. Method of manufacturing a π-type thermoelectric module for power generation, which is bonded to each of the lower substrate.
The method of claim 11,
The metal gauze comprises a metal selected from the group consisting of Au, Ag, Pd, Ni, Cu and combinations thereof, the method of manufacturing a π-type thermoelectric module for power generation.

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