KR102049010B1

KR102049010B1 - Thermoelectric module

Info

Publication number: KR102049010B1
Application number: KR1020150129936A
Authority: KR
Inventors: 김동식; 이승협; 이재기; 박철희; 이대기; 최현우
Original assignee: 주식회사 엘지화학
Priority date: 2015-09-14
Filing date: 2015-09-14
Publication date: 2019-11-26
Also published as: KR20170032111A

Abstract

The present invention discloses a thermoelectric module and a thermoelectric generator including the same, wherein the output is improved and the thermal stability is excellent and the durability is improved even at a high temperature. Thermoelectric module according to the present invention, the electrode consisting of a metal material; A p-type leg bonded to one end of the electrode and composed of a BiTe-based thermoelectric material; And an n-type leg bonded to the other end of the electrode and composed of a skuterudite-based thermoelectric material.

Description

Thermoelectric module {Thermoelectric module}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to thermoelectric technology, and more particularly, to a thermoelectric module having improved output and excellent thermal stability.

If there is a temperature difference across the material in the solid state, a difference in the concentration of the carrier (electrons or holes) having thermal dependence occurs, which is represented by an electrical phenomenon called thermoelectric power, that is, a thermoelectric phenomenon. As such, thermoelectric phenomena means the reversible and direct conversion of energy between temperature differences and electrical voltages. These thermoelectric phenomena can be classified into thermoelectric power generation, which produces electrical energy, and thermoelectric cooling / heating, which causes a temperature difference between both ends by supplying electricity.

Thermoelectric materials that exhibit thermoelectric phenomena, that is, thermoelectric semiconductors, have been researched due to their environmentally friendly and sustainable advantages in power generation and cooling. In addition, since the power can be directly generated from industrial waste heat, automotive waste heat, etc., and thus useful for improving fuel efficiency or CO ₂ reduction, interest in thermoelectric materials is increasing.

The thermoelectric module may be a pair of p-n thermoelectric legs including a p-type thermoelectric leg for moving holes to move thermal energy and an n-type thermoelectric leg for moving electrons to move thermal energy. The thermoelectric module may include an electrode connecting the p-type thermoelectric leg and the n-type thermoelectric leg.

For thermoelectric modules, thermal stability is required with excellent output. In particular, thermoelectric modules such as thermoelectric generators are often used at temperatures much higher than room temperature, and therefore, even at such high temperature conditions, thermal stability needs to be maintained above a certain level.

Accordingly, an object of the present invention is to provide a thermoelectric module and a thermoelectric generator including the same, which have been developed to solve the above problems and have excellent thermal stability and improved durability even at high temperatures.

Other objects and advantages of the present invention can be understood by the following description, and will be more clearly understood by the embodiments of the present invention. Also, it will be readily appreciated that the objects and advantages of the present invention may be realized by the means and combinations thereof indicated in the claims.

Thermoelectric module according to the present invention for achieving the above object, the electrode consisting of a metal material; A p-type leg bonded to one end of the electrode and composed of a BiTe-based thermoelectric material; And an n-type leg bonded to the other end of the electrode and composed of a skuterudite-based thermoelectric material.

Here, the p-type leg and the n-type leg may be formed in a columnar shape with a different horizontal cross-sectional area.

In addition, the n-type leg may be configured to have a horizontal cross-sectional area smaller than the p-type leg.

Further, the ratio of the horizontal cross-sectional area of the p-type leg to the horizontal cross-sectional area of the n-type leg may be configured to be greater than 1 and 5 or less.

In addition, the BiTe-based thermoelectric material may be represented by the following Chemical Formula 1.

Bi _x Sb ₂ _- _x Te ₃

In Formula 1, 0 <x ≦ 2.

The squaterite-based thermoelectric material may be based on Co ₄ Sb ₁₂ .

In addition, the thermoelectric generator according to the present invention for achieving the above object may include a thermoelectric module according to the present invention.

According to one aspect of the present invention, a hybrid type thermoelectric module using different types of thermoelectric materials for p-type legs and n-type legs is proposed.

In particular, according to an embodiment of the present invention, the size of the p-type leg and n-type leg may be configured differently.

Therefore, according to this aspect of the present invention, the output of the thermoelectric module is improved, excellent thermal stability can be secured, and durability can be improved.

In particular, according to one aspect of the present invention, a thermoelectric module exhibiting excellent performance at a temperature condition of 300 degrees or less may be provided.

The following drawings attached to this specification are illustrative of preferred embodiments of the present invention, and together with the detailed description of the invention to serve to further understand the technical spirit of the present invention, the present invention is a matter described in such drawings It should not be construed as limited to.
1 is a view schematically showing a thermoelectric module according to an embodiment of the present invention.
FIG. 2 is an enlarged view of portion A of FIG. 1.
3 is a top view schematically showing the form of a thermoelectric module used in the analysis of the examples and comparative examples of the present invention.
FIG. 4 is a side view of a unit couple including one p-type leg and one n-type leg in the configuration of FIG. 3.
FIG. 5 is a graph showing an ANSYS simulation output result compared to thermoelectric modules according to one embodiment of the present invention and a comparative example. FIG.
6 is a graph illustrating a result of measuring efficiency according to external resistance through an ANSYS simulation of a thermoelectric module according to various embodiments of the present disclosure.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, terms or words used in the present specification and claims should not be construed as being limited to the common or dictionary meanings, and the inventors should properly explain the concept of terms in order to best explain their own invention. Based on the principle that can be defined, it should be interpreted as meaning and concept corresponding to the technical idea of the present invention.

Therefore, the embodiments described in the specification and the drawings shown in the drawings are only the most preferred embodiment of the present invention and do not represent all of the technical spirit of the present invention, various modifications that can be replaced at the time of the present application It should be understood that there may be equivalents and variations.

1 is a view schematically showing a thermoelectric module according to an embodiment of the present invention.

Referring to FIG. 1, a thermoelectric module according to the present invention includes an electrode 100, a p-type thermoelectric leg 200, and an n-type thermoelectric leg 300.

The electrode may be composed of an electrically conductive material, in particular a metal material. For example, the electrode may be made of Cu, Al, Ni, Au, Ti, or an alloy thereof. In addition, the electrode may be configured in a plate shape. For example, the electrode may be configured in the form of a copper plate. In particular, the electrode may be configured in the form of a rectangular plate relatively long in one direction so that the p-type leg and the n-type leg can be easily bonded to both ends.

The p-type leg is bonded to one end of the electrode and may be composed of a p-type thermoelectric material. In particular, the p-type leg may be composed of a BiTe-based thermoelectric material.

For example, the p-type leg may be composed of a BiTe-based thermoelectric material represented by Formula 1 below.

Bi _x Sb ₂ _- _x Te ₃ .

Here, x may have a range of 0 <x≤2.

The n-type leg is bonded to the other end of the electrode, it may be composed of n-type thermoelectric material. In particular, the n-type leg may be composed of a skutterudite-based thermoelectric material.

For example, the n-type leg may be composed of a skuterrudite-based thermoelectric material having Co ₄ Sb ₁₂ as a basic structure.

A Co ₄ Sb ₁₂ as an example of Surgical Teruel die teugye thermoelectric material of the basic structure, there may be mentioned a compound semiconductor represented by Formula 2 below.

In _x M _y Co _4-ma A _m Sb _12-nzb X _n Q ' _z

Where M is Ca, Sr, Ba, Ti, V, Cr, Mn, Cu, Zn, Ag, Cd, Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, At least one selected from the group consisting of Er, Tm, Yb, and Lu, A is at least one selected from the group consisting of Fe, Ni, Ru, Rh, Pd, Ir, and Pt, and X is Si, Ga, At least one selected from the group consisting of Ge and Sn, and Q 'is at least one selected from the group consisting of O, S, and Se, and 0 <x <1, 0 <y <1, 0 ≦ m ≦ 1 , 0 ≦ n <9, 0 <z ≦ 2, 0 ≦ a ≦ 1, 0 <b ≦ 3 and 0 <n + z + b <12.

As described above, the thermoelectric module according to the present invention may be formed of a series of thermoelectric modules having different p-type legs and n-type legs bonded to both ends of the electrode. In particular, the thermoelectric module according to the present invention may be configured in the form of a hybrid thermoelectric module in which a chalcogenide-based BiTe-based material is used as the p-type leg and a skuterrudite-based material is used as the n-type leg.

According to this configuration of the present invention, the output of the thermoelectric module can be improved, and the durability can be improved by ensuring excellent thermal stability.

In particular, in the case of a thermoelectric module according to an aspect of the present invention, by using a non-BiTe-based skuterrudite-based thermoelectric material as the n-type leg, it can be used more suitably at a temperature of 300 degrees or less.

On the other hand, the p-type legs and n-type legs, may be prepared in a manner of going through the mixing step of each raw material, the synthesis step through the heat treatment and the sintering step. However, the present invention is not necessarily limited to the specific manufacturing method of such thermoelectric legs.

The electrode may be connected between a thermoelectric leg, more specifically, between a p-type leg and an n-type leg. For example, the electrode may have one end coupled to the p-type leg and the other end coupled to the n-type leg. Thus, the n-type leg and the p-type leg can be electrically connected to each other by an electrode.

In particular, the thermoelectric module according to the present invention may include a plurality of p-type legs and a plurality of n-type legs, as shown in FIG. The electrodes may be coupled to both ends of the thermoelectric legs, respectively. Therefore, the electrode may be provided in plural in the thermoelectric module according to the present invention.

The electrode may be attached to an end of each thermoelectric leg. For example, some electrodes may have a bottom surface attached to the top of the n-type leg and the top of the p-type leg. In addition, the other electrode, the upper surface may be attached to the bottom of the n-type leg and the bottom of the p-type leg. At this time, the electrical connection between the n-type leg and the p-type leg through the electrode may be connected in series. For example, the electrodes respectively connected to the top and bottom of one n-type leg may be connected to different p-type legs.

Meanwhile, one n-type leg and one p-type leg may be coupled to each electrode. However, the present invention is not necessarily limited to these embodiments, and a plurality of p-type legs and a plurality of n-type legs may be coupled to one electrode.

The p-type legs and n-type legs may be formed in a pillar shape. For example, the p-type leg and n-type leg may be formed in a cylindrical or prismatic form.

In particular, the p-type leg and the n-type leg, may be formed in a columnar shape with a different horizontal cross-sectional area. This will be described in more detail with reference to FIG. 2.

FIG. 2 is an enlarged view of portion A of FIG. 1.

Referring to FIG. 2, both the p-type leg and the n-type leg may be configured in a square pillar shape. That is, the p-type leg and the n-type leg may be formed in a cross-sectional area when cut in the horizontal direction parallel to the electrode, that is, the horizontal cross-sectional area in a square.

Here, the horizontal cross-sectional area of the p-type leg and the horizontal cross-sectional area of the n-type leg may be represented by A _p and A _n , respectively, and they may have different sizes.

For example, in the configuration shown in FIG. 2, the horizontal length and the vertical length of the horizontal cross-sectional area of the p-type leg are called W2 and L2, respectively, and the horizontal length and the vertical length of the n-type leg are called W3 and L3, respectively. In this case, the horizontal cross-sectional area A _p of the p-type leg may be represented by W2 × L2, and the horizontal cross-sectional area A _n of the n-type leg may be represented by W3 × L3. In this case, the thermoelectric module according to the present invention may be configured such that A _p (that is, W2 × L2) and A _n (that is, W3 × L3) have different values.

Moreover, the thermoelectric module according to the present invention can be configured such that the n-type legs have a smaller horizontal cross-sectional area than the p-type legs. For example, in the configuration of FIG. 2, the thermoelectric module can be configured to have a relationship of A _p > A _n .

As a more specific example, in the configuration of FIG. 2, the p-type leg may be configured such that both the horizontal length W2 and the vertical length L2 are 3.6 mm. In this case, the n-type leg may be configured such that both the horizontal length W3 and the vertical length L3 are less than 3.6 mm, 3.4 mm, 3.2 mm, 3.0 mm and the like.

According to this configuration of the present invention, the p-type leg and the n-type leg is not only composed of different series as BiTe-based and skuterudite-based, but also different in size, so that the efficiency of the thermoelectric module can be optimized.

In particular, the ratio of the horizontal cross-sectional area of the p-type leg to the horizontal cross-sectional area of the n-type leg may be greater than 1 and 5 or less. And this can be expressed by the following relationship.

1 <A _p / A _n ≤5

Furthermore, the ratio A _p / A _n of the horizontal cross-sectional area of the p-type leg to the horizontal cross-sectional area of the n-type leg may be greater than 1 and less than 2.

For example, in the above embodiment, both the horizontal length W2 and the vertical length L2 of the p-type leg are 3.6 mm, and the horizontal length W3 and the vertical length L3 of the n-type leg are both 3.4 mm. When A _p / A _n may be approximately 1.121.

As another example, in the above embodiment, both the horizontal length W2 and the vertical length L2 of the p-type leg are 3.6 mm, and the horizontal length W3 and the vertical length L3 of the n-type leg are both 3.2 mm. When A _p / A _n may be approximately 1.266.

As another example, in the above embodiment, both the horizontal length W2 and the vertical length L2 of the p-type leg are 3.6 mm, and the horizontal length W3 and the vertical length L3 of the n-type leg are all 3.0 mm. When, A _p / A _n may be approximately 1.440.

As such, in the thermoelectric module according to the present invention, the ratio (A _p / A _n ) of the horizontal cross-sectional area of the p-type leg to the horizontal cross-sectional area of the n-type leg may be configured to be greater than one.

In addition, the height (H) of the p-type legs and n-type legs, the thickness (T1) or the length (L1) of the electrode can be implemented in various ways. For example, H may be 2.0 mm, T1 may be 0.3 mm, and L1 may be 9.0 mm. However, the present invention is not necessarily limited to a specific size of such thermoelectric legs or electrodes.

Meanwhile, the thermoelectric module according to the present invention may further include a substrate as shown in FIG. 1.

The substrate may be made of an electrically insulating material. For example, the substrate may be made of a ceramic material such as alumina. However, the present invention is not limited to the specific material of the substrate. For example, the substrate may be made of various materials such as sapphire, silicon, SiN, SiC, AlSiC, quartz, and the like.

The substrate may be disposed outside the thermoelectric module to electrically insulate various components of the thermoelectric module, such as electrodes, from the outside and protect the thermoelectric module from external physical or chemical elements. In addition, the substrate can be maintained so as to maintain the basic form of the thermoelectric module by mounting an electrode or the like. For example, as shown in FIG. 1, the substrate may be provided at both the upper portion of the electrode coupled to the upper portion of the thermoelectric leg and the lower portion of the electrode coupled to the lower portion of the thermoelectric leg. In this configuration, the electrodes may be provided on the surface of the substrate in various ways. For example, the electrode may be formed on the surface of the substrate in various ways such as direct bonded copper (DBC), active metal brazing (ABM), and the like. Alternatively, the electrode may be provided on the substrate through an adhesive or the like.

The thermoelectric module according to the present invention can be applied to various devices that apply thermoelectric technology. In particular, the thermoelectric module according to the present invention can be applied to a thermoelectric generator. That is, the thermoelectric generator according to the present invention may include the thermoelectric module according to the present invention.

Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples. However, the embodiment according to the present invention may be modified in various other forms, and the scope of the present invention should not be construed as being limited to the embodiments described below. The embodiments of the present invention are provided to more completely explain the present invention to those skilled in the art.

Comparative example

P-type legs and n-type legs were configured as BiTe-based thermoelectric materials, and the finite element method (FEM) using ANSYS simulation was performed to analyze the characteristics of the thermoelectric module. At this time, the temperature characteristics of BiTe-type p-type legs used in the analysis are as shown in Table 1 below, and the temperature characteristics of BiTe-type n-type legs used in the analysis are as shown in Table 2 below. And the form of the thermoelectric module used for analysis is as showing in FIG.3 and FIG.4. That is, FIG. 3 is a top view schematically showing the shape of the thermoelectric module used in the analysis of the examples and comparative examples of the present invention, and FIG. 4 includes one p-type leg and one n-type leg in the configuration of FIG. 3. A side view of a unit couple. However, for convenience of description, the upper substrate is not displayed in FIG. 3, and neither the upper substrate nor the lower substrate is displayed in FIG. 4.

3 and 4, both the p-type leg and the n-type leg of the thermoelectric module used in the analysis, the horizontal length and vertical length were 3.6 mm and 2.0 mm respectively. In addition, the p-type leg-n type leg pair is configured to include 32 pairs in the thermoelectric module. In addition, the electrodes included in the thermoelectric module were 8.6 mm long, 3.6 mm long, and 0.3 mm high. Moreover, the board | substrate contained in a thermoelectric module was 41.0 mm in width | variety length and a vertical length, respectively, and was comprised in height 0.635 mm.

Example One

ANSYS simulation was performed by configuring a thermoelectric module having the same shape as the comparative example, but changing only the material type of the n-type leg. More specifically, in the case of Example 1, instead of the BiTe-based thermoelectric material having the properties shown in Table 2, n-type legs were formed by using the skuterudite-based thermoelectric material having the properties shown in Table 3. In other words, in the case of Example 1, a thermoelectric module including a BiTe p-type leg having the characteristics shown in Table 1 and a skuterrudite n-type leg having the characteristics shown in Table 3 is illustrated in FIGS. 3 and 4. It was configured in the form as shown.

For the thermoelectric modules of Comparative Example and Example 1 configured as described above, the output was compared through ANSYS simulation, and the results are shown in FIG. At this time, the high temperature side temperature of the thermoelectric module used in the analysis is 300 ℃ and the low temperature side temperature was composed of 50 ℃, the electrode is a copper electrode, the resistance of 16.78 nΩ · m and 401 W · m ⁻¹ · K ^-1 It was intended to have thermal conductivity. In addition, an analysis was performed in consideration of thermal contact conductance (TCC) occurring in an actual thermoelectric module.

Looking at the results analyzed by ANSYS simulation with reference to Figure 5, compared to the thermoelectric module of the comparative example in which both the p-type legs and n-type legs are composed of BiTe-based material, the p-type legs are composed of BiTe-based material and the n-type legs It can be seen that the output of the thermoelectric module of Example 1 composed of the terudite-based material is high. More specifically, at 40000 W / m ² ℃, the output of the thermoelectric module of the comparative example is 13.930 W, while the output of the thermoelectric module of Example 1 is 16.455 W, which is about 18% improved compared to the comparative example Can be confirmed.

According to the experimental results, in the case of a hybrid thermoelectric module in which p-type legs and n-type legs are differently composed of BiTe-based materials and skuttrudite-based materials, as in the present invention, both p-type legs and n-type legs are BiTe-based. Compared with the configured thermoelectric module, it can be seen that the output performance is remarkably improved.

In addition, the thermoelectric module according to the present invention may be configured in a columnar shape having different horizontal cross-sectional areas with respect to the p-type leg and the n-type leg. In order to confirm the effect on this was configured the following additional examples.

Example 2

The unit couple as shown in FIG. 4 is configured as described in Example 1, but the size of the horizontal cross-sectional area of the n-type leg is different from that of Example 1, and the rest of the conditions are configured identically. That is, in the configuration of Example 1, both the n-type leg and the p-type leg were configured to have the same horizontal length and vertical length as 3.6 mm, but in the configuration of Example 2, the horizontal length and vertical length of the n-type leg were Each of them consisted of 3.4 mm rather than 3.6 mm, so that the size of the horizontal cross-sectional area of the squaterite n-type legs and the BiTe p-type legs were different.

Example 3

Compared to Example 1, only the horizontal cross-sectional area size of the n-type leg is differently configured, and the rest of the conditions are the same as the unit couple. That is, in the configuration of Example 1, the horizontal length and the vertical length of the n-type legs were configured to be 3.2 mm, respectively, so that the size of the horizontal cross-sectional area of the squaterite n-type legs and the BiTe-based p-type legs was different.

Example 4

Compared to Example 1, only the horizontal cross-sectional area size of the n-type leg is differently configured, and the rest of the conditions are the same as the unit couple. In other words, in the configuration of Example 1, the horizontal length and the vertical length of the n-type leg were configured to be 3.0 mm, respectively, so that the size of the horizontal cross-sectional area of the squaterite n-type leg and the BiTe-type p-leg was different.

For the thermoelectric modules of Examples 2 to 4 and the thermoelectric modules of Example 1 configured as described above, the efficiency according to the external resistance was measured through ANSYS simulation, and the results are shown in FIG. 6. At this time, the conditions of the ANSYS simulation can be said to be the same as the conditions described with respect to the comparative example and Example 1, unless otherwise noted.

Referring to the simulation result shown in FIG. 6, compared with Example 1 in which the horizontal cross-sectional areas of the p-type leg and the n-type leg are identical to each other, the second to fourth embodiments have different horizontal cross-sectional areas of the p-type leg and the n-type leg. In the case of 4, it can be seen that the maximum efficiency is improved. Specifically looking, the change in the result of Figure 6, in a state in which the horizontal cross-sectional area of the p-type legs fixed to 12.96 mm ^2, with the cross sectional area of the n-type legs ^{12.96 mm 2, 11.56 mm 2,} 10.24 mm 2, 9.00 mm 2 As time goes by, the maximum efficiency is gradually improved. In particular, looking at Example 4, it can be seen that the maximum efficiency is approximately 7.6% under load matching conditions, which is a significant improvement compared to Example 1, which shows a maximum efficiency of approximately 7.1%. .

As described above, in the case of the thermoelectric module according to an aspect of the present invention, the horizontal cross-sectional area of the p-type leg and the n-type leg are configured differently, in particular, the horizontal cross-sectional area of the p-type leg is smaller than the horizontal cross-sectional area of the n-type leg. It can be seen that by making it large, the efficiency of the thermoelectric module can be improved.

As described above, although the present invention has been described by way of limited embodiments and drawings, the present invention is not limited thereto and is intended by those skilled in the art to which the present invention pertains. Of course, various modifications and variations are possible within the scope of equivalents of the claims to be described.

100: electrode
200: p-type leg
300: n-type leg
400: substrate

Claims

A plurality of electrodes made of a metallic material;
A p-type leg bonded to one end of the electrode and composed of a BiTe-based thermoelectric material; And
N-type legs bonded to the other end of the electrode and composed of a skuterrudite-based thermoelectric material
Including,
Some electrodes of the plurality of electrodes may be attached to upper ends of the p-type legs formed of the BiTe-based thermoelectric material and upper ends of the n-type legs formed of the squaterite-based thermoelectric material, respectively. Some electrodes may be attached to a lower end of a p-type leg formed of the BiTe-based thermoelectric material and a lower end of an n-type leg formed of the skudrudite-based thermoelectric material, respectively, and the p-type leg formed of the BiTe-based thermoelectric material The n-type leg composed of the skuterrudite-based thermoelectric material is disposed on the same plane.

The method of claim 1,
The p-type leg and the n-type leg, the thermoelectric module, characterized in that formed in the shape of a column having a different horizontal cross-sectional area.

The method of claim 2,
And the n-type leg has a horizontal cross-sectional area smaller than the p-type leg.

The method of claim 3,
And the ratio of the horizontal cross-sectional area of the p-type leg to the horizontal cross-sectional area of the n-type leg is greater than 1 and 5 or less.

The method of claim 1,
The BiTe-based thermoelectric material is a thermoelectric module, characterized in that represented by the formula (1).
<Formula 1>
Bi _x Sb ₂ _- _x Te ₃
In Formula 1, 0 <x ≦ 2.

The method of claim 1,
The thermoelectric module of the squaterite-based thermoelectric material, characterized in that the basic structure of Co ₄ Sb ₁₂ .

Thermoelectric power generation device comprising a thermoelectric module according to any one of claims 1 to 6.