THERMOELECTRIC MODULE AND THERMOELECTRIC GENERATOR

A thermoelectric module and a thermoelectric generator, the thermoelectric module includes a first substrate provided with a first electrode, a second substrate provided with a second electrode and disposed opposite to the first substrate, and a plurality of thermoelectric elements disposed between the first substrate and the second substrate and electrically connected to the first electrode and the second electrode. The thermoelectric elements may be sintered and bonded to each other with bonding layers containing silver (Ag) to be electrically connected between the first substrate and the second substrate, and may include Skutterudite-based thermoelectric elements electrically connected to the first electrode and BiTe-based thermoelectric elements connected to the Skutterudite-based thermoelectric elements with the bonding layers and electrically connected to the second electrode.

TECHNICAL FIELD

This application claims priority to and the benefit of Korean Patent Application No. 10-2017-0105104 filed in the Korean Intellectual Property Office on Aug. 18, 2017, the entire contents of which are incorporated herein by reference.

The present invention relates to a thermoelectric module and a thermoelectric generator in which quality and thermal stability of the thermoelectric module are improved.

BACKGROUND ART

When there is a temperature difference between opposite ends of a solid-state material, there is generated a difference in concentration of carriers (electrons or holes) having a heat dependence, which appears as an electric phenomenon called thermo-electromotive force, that is, a thermoelectric phenomenon.

The thermoelectric phenomenon refers to a direct energy conversion between the temperature difference and electric voltage.

The thermoelectric phenomenon may be classified into a thermoelectric generation which generates electric energy and a thermoelectric cooling/heating which causes the temperature difference at the opposite ends of the material by power supply.

A thermoelectric material which exhibits the thermoelectric phenomenon, i.e. a thermoelectric semiconductor, has been studied in many ways because the material has advantages of being environmentally friendly and sustainable in processes of power generation and cooling.

Furthermore, interest in such a thermoelectric material is further increasing because the material may directly produce power from industrial waste heat and automobile waste heat, and may thus be used in technology useful for fuel efficiency improvement and CO2reduction.

A basic unit of a thermoelectric module may be a uni-couple of p-n thermoelectric elements including a p-type thermoelectric element (TE) through which a current flows by a hole carrier and an n-type thermoelectric element through which a current flows by an electron. The thermoelectric module may also include an electrode which connect the p-type thermoelectric element and the n-type thermoelectric element with each other.

The thermoelectric element may be generally formed in a rod-like or columnar structure, and the power proportional to the square of the temperature difference may be obtained in a state in which one end of the material is maintained to be at a high temperature and the other end thereof is maintained to be at a low temperature.

The thermoelectric material used for such a thermoelectric element has a use temperature range in which a performance thereof is optimized, and a plurality of thermoelectric materials are bonded and used to follow the temperature difference in order to maximize power generation output or efficiency at the use temperature. Here, an element formed by bonding the thermoelectric materials to each other in series both mechanically structurally and electrically is called a segment thermoelectric element.

Meanwhile, sintering temperatures of a Skutterudite-based thermoelectric material and a BiTe-based thermoelectric material are different from each other. The quality and thermal stability of the thermoelectric module may thus be deteriorated in a process of manufacturing the thermoelectric element by bonding the above thermoelectric materials to each other.

DISCLOSURE

Technical Problem

The present invention has been made in an effort to provide a thermoelectric module and a thermoelectric generator having advantages of improved output, efficiency characteristic and thermal stability.

Technical Solution

An exemplary embodiment of the present invention provides: a first substrate provided with a first electrode; a second substrate provided with a second electrode and disposed opposite to the first substrate; and a plurality of thermoelectric elements disposed between the first substrate and the second substrate and electrically connected to the first electrode and the second electrode.

The thermoelectric elements may be sintered and bonded to each other with bonding layers containing silver (Ag) to be electrically connected between the first substrate and the second substrate, and include Skutterudite-based thermoelectric elements electrically connected to the first electrode and BiTe-based thermoelectric elements connected to the Skutterudite-based thermoelectric elements with the bonding layers and electrically connected to the second electrode.

The thermoelectric elements may include first thermoelectric elements electrically connected between the first substrate and the second substrate, and second thermoelectric elements electrically connected between the first substrate and the second substrate in a state in which the second thermoelectric elements are spaced apart from the first thermoelectric elements.

The first thermoelectric elements may be formed of at least two or more thermoelectric elements bonded to each other with the bonding layer.

The first thermoelectric elements may include a first Skutterudite-based thermoelectric element electrically connected to the first electrode and a first

BiTe-based thermoelectric element connected to the first Skutterudite-based thermoelectric element with the bonding layer and electrically connected to the second electrode.

Opposite ends of the first thermoelectric elements may each be electrically connected to the first electrode and the second electrode with the bonding layers.

The second thermoelectric elements may be formed of at least two or more thermoelectric elements bonded to each other with the bonding layer.

The second thermoelectric elements may include a second Skutterudite-based thermoelectric element electrically connected to the first electrode and a second BiTe-based thermoelectric element connected to the second Skutterudite-based thermoelectric element with the bonding layer and electrically connected to the second electrode.

Opposite ends of the second thermoelectric elements may each be electrically connected to the first electrode and the second electrode with the bonding layers.

The first thermoelectric elements may be p-type thermoelectric semiconductors, and the second thermoelectric elements may be n-type thermoelectric semiconductors.

The thermoelectric module may further include a diffusion barrier layer disposed between the first substrate and the first thermoelectric elements.

The thermoelectric module may further include a diffusion barrier layer disposed between the second substrate and the second thermoelectric elements.

The thermoelectric module may further include a diffusion barrier layer disposed between the first Skutterudite-based thermoelectric element and the first BiTe-based thermoelectric element.

The thermoelectric module may further include a diffusion barrier layer disposed between the second Skutterudite-based thermoelectric element and the second BiTe-based thermoelectric element.

The diffusion barrier layer may be formed of at least one selected from the group consisting of hafnium (Hf), titanium nitride (TiN), zirconium (Zr), and Mo—Ti.

According to an embodiment of the present invention, a thermoelectric generator may include the thermoelectric module as described above. The thermoelectric generator may include at least one high temperature block connected to the thermoelectric module, a low temperature block connected to the thermoelectric module at a side surface opposite to the high temperature block, and a heat dissipating member disposed in the high temperature block and the low temperature block.

Advantageous Effects

According to an embodiment of the present invention, output, efficiency characteristic and thermal stability of the thermoelectric module may be improved by sintering and bonding the first thermoelectric elements to each other and the second thermoelectric elements to each other, using a paste containing silver (Ag).

According to an embodiment of the present invention, the output and efficiency characteristic of the thermoelectric module may be improved, so that the power generation output and efficiency of the thermoelectric generator may be improved.

MODE FOR INVENTION

Hereinafter, embodiments of the present invention are described in detail with reference to the accompanying drawings so that those skilled in the art may easily practice the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention.

Throughout this specification and the claims that follow, when it is described that an element such as a layer, a film, a region, a plate or the like is referred to as being “on” or “above” another element, it is to be understood that the element may be directly “on” another element or “above” another element including other elements therebetween. In addition, the word “on” or “above” means to be located above or below the object portion and does not necessarily mean that the object is located on the upper side with respect to the gravitational direction.

FIG. 1is a cross-sectional view schematically showing main components of a uni-couple of a thermoelectric module according to an embodiment of the present invention.

According to an embodiment of the present invention, as shown inFIG. 1, a uni-couple100of a thermoelectric module may include: a first substrate10provided with a first electrode11; a second substrate20provided with a second electrode21and disposed opposite to the first substrate10; and a plurality of thermoelectric elements30disposed between the first substrate10and the second substrate20and electrically connected to the first electrode11and the second electrode21. Here, the thermoelectric elements30may be bonded to each other with bonding layers40containing silver (Ag).

The thermoelectric elements30may include Skutterudite-based thermoelectric elements31aand33aelectrically connected to the first electrode11, and BiTe-based thermoelectric elements31band33bconnected to the Skutterudite-based thermoelectric elements31aand33awith the bonding layers40and electrically connected to the second electrode.

The Skutterudite-based thermoelectric elements31aand33amay include a first Skutterudite-based thermoelectric element31aand a second Skutterudite-based thermoelectric element33a,and the BiTe-based thermoelectric elements31band33bmay include a first BiTe-based thermoelectric element31band a second BiTe-based thermoelectric element33b.

Meanwhile, the first substrate10and the second substrate20may be respectively disposed on opposite ends of the thermoelectric elements30, having the thermoelectric elements30interposed therebetween, to support the thermoelectric elements.

The first substrate10may be used as a high-temperature portion in the present embodiment. The first substrate10has a flat surface facing the thermoelectric elements30and may stably support the thermoelectric elements30.

The first substrate10may be formed of a ceramic material such as alumina or aluminum nitride (AlN).

The second substrate20may be used as a low-temperature portion in the present embodiment. The second substrate20may be disposed opposite to the first substrate10having the thermoelectric elements30interposed therebetween and stably support the thermoelectric elements30together with the first substrate10

The second substrate20may be formed of a ceramic material such as alumina or AlN.

A heat dissipating member (not shown) may also be formed on the second substrate20to improve heat dissipation efficiency.

Meanwhile, the thermoelectric elements30may be disposed in a state in which the thermoelectric elements30are electrically connected between the first substrate10and the second substrate20by the first electrode11and the second electrode21.

The thermoelectric elements30may include first thermoelectric elements31electrically connected between the first substrate10and the second substrate20and second thermoelectric elements33electrically connected between the first substrate10and the second substrate20in a state in which the second thermoelectric elements33are spaced apart from the first thermoelectric elements31.

The first thermoelectric elements31may be formed of at least two or more thermoelectric elements bonded to each other with the bonding layer40and disposed between the first substrate10and the second substrate20. Opposite ends of the first thermoelectric elements31may each be electrically connected to the first electrode11and the second electrode21with bonding layers40.

The first thermoelectric elements31may be formed of p-type thermoelectric semiconductors and include a first Skutterudite-based thermoelectric element31aelectrically connected to the first electrode11and a first BiTe-based thermoelectric element31belectrically connected to the second electrode21.

That is, the first thermoelectric elements31may have a first Skutterudite-based thermoelectric element31athat maximizes performance efficiency at a relatively high temperature region in a portion electrically connected to the first substrate10.

The first thermoelectric elements31may have a first BiTe-based thermoelectric element31bthat maximizes performance efficiency at a relatively low temperature region in a portion electrically connected to the second substrate20.

In the first thermoelectric elements31, the first skutertudite-based thermoelectric element31aand the first BiTe-based thermoelectric element31bmay be bonded to each other with the bonding layer40.

That is, the bonding layer40formed of a paste containing silver (Ag) may sinter and bond the first Skutterudite-based thermoelectric element31aand the first BiTe-based thermoelectric element31bto each other.

Here, the first Skutterudite-based thermoelectric element31aand the first BiTe-based thermoelectric elements31bmay be sintered and bonded to each other with the bonding layer40before being electrically connected to the first substrate10and the second substrate20

Meanwhile, the thermoelectric module may further include a diffusion barrier layer50disposed between the first Skutterudite-based thermoelectric element31aand the first BiTe-based thermoelectric element31b.

A diffusion barrier layer50may prevent thermoelectric materials from diffusing to each other.

A diffusion barrier layer50may be formed of at least one selected from the group consisting of hafnium (Hf), titanium nitride (TiN), zirconium (Zr), and Mo—Ti.

In addition to the diffusion barrier layer50formed between the first Skutterudite-based thermoelectric element31aand the first BiTe-based thermoelectric element31bas described above, the thermoelectric module may further include a diffusion barrier layer formed between the first substrate10and the first thermoelectric elements31and a diffusion barrier layer formed between the second substrate20and the first thermoelectric elements31.

The second thermoelectric elements33may be formed in a shape identical or similar to that of the first thermoelectric elements31, and may be disposed between the first substrate10and the second substrate20in a state in which the second thermoelectric elements33are spaced apart from the first thermoelectric elements31.

The second thermoelectric elements33may also be adapted to have an appropriate size or shape to improve power generation efficiency. The second thermoelectric elements33may be formed of n-type thermoelectric semiconductors and include a second Skutterudite-based thermoelectric element33aelectrically connected to the first electrode11and a second BiTe-based thermoelectric element33belectrically connected to the second electrode21.

That is, the second thermoelectric elements33may have a second Skutterudite-based thermoelectric element33athat maximizes performance efficiency at a relatively high temperature region in a portion electrically connected to the first substrate10.

The second thermoelectric elements33may have a second BiTe-based thermoelectric element31bthat maximizes performance efficiency at a relatively low temperature region in a portion electrically connected to the second substrate20.

In the second thermoelectric elements33, the second skutertudite-based thermoelectric element33aand the second BiTe-based thermoelectric element33bmay be bonded to each other with the bonding layer40.

That is, the bonding layer40formed of a paste containing silver (Ag) may sinter and bond the second Skutterudite-based thermoelectric element33aand the second BiTe-based thermoelectric element33bto each other.

Here, the second Skutterudite-based thermoelectric element33aand the second BiTe-based thermoelectric element33bmay be sintered and bonded to each other with the bonding layer40before being electrically connected to the first substrate10and the second substrate20.

Meanwhile, the thermoelectric module may further include a diffusion barrier layer50disposed between the second Skutterudite-based thermoelectric element33aand the second BiTe-based thermoelectric element33b.

A diffusion barrier layer50may prevent the thermoelectric materials from diffusing to each other. In addition to the diffusion barrier layer50formed between the second Skutterudite-based thermoelectric element33aand the second BiTe-based thermoelectric element33bas described above, the thermoelectric module may further include a diffusion barrier layer formed between the first substrate10and the second thermoelectric elements33and a diffusion barrier layer formed between the second substrate20and the second thermoelectric elements33.

As described above, the uni-couple100of the thermoelectric module of the present embodiment may improve the output, efficiency characteristic and thermal stability of the thermoelectric module by sintering and bonding the first thermoelectric elements to each other and the second thermoelectric elements to each other, using a paste containing silver (Ag).

FIG. 2is a schematic view illustrating an output characteristic of the thermoelectric module according to an embodiment of the present invention; andFIG. 3is a schematic view illustrating efficiency characteristic of the thermoelectric module according to an embodiment of the present invention.

That is,FIGS. 2 and 3are graphs showing the output and efficiency characteristic of a segment module depending on a temperature difference after manufacturing the thermoelectric module constituted by31uni-couples100of the thermoelectric module.

To be specific, as shown inFIG. 2, the power generation output of 7.49 W, 11.52 W, and 15.54 W is obtained at 281° C., 356° C., and 447° C., respectively.

As shown inFIG. 3, high efficiency of 8.99%, 10.32%, or 10.72% is obtained in each temperature difference as a result of measuring the power generation efficiency.

In general, power generation efficiency of the Skutterudite-based thermoelectric elements is about 6.5% and therefore, the segment thermoelectric element is confirmed to have considerably high power generation efficiency.

According to an embodiment of the present invention, a thermoelectric generator may include at least one high temperature block connected to the thermoelectric module, a low temperature block connected to the thermoelectric module at a side surface opposite to the high temperature block, and a heat dissipating member disposed in the low temperature block.

The output and efficiency characteristic of the thermoelectric module are thus improved, so that the power generation efficiency of the thermoelectric generator may be improved.

While this invention has been described in connection with what is s presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. On the contrary, it is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.