What is the material for thermoelectric power generation?

August 26, 2020
August 26, 2020 Longchang Chemical

1. In recent years, with the continuous development of mobile communication technology, material microprocessing technology, and information technology, the continuous miniaturization and multi-functionalization of mobile appliances such as notebook computers can also be applied to thermoelectric devices in power supplies, cooling systems, and decentralized propulsion systems.

2. Continue to develop towards miniaturization. The thermoelectric device developed by the electric refrigeration effect has a lot of advantages that the compression refrigerator is incomparable, such as small size, light weight, no mechanical transmission parts, fast response speed, long service life, no noise, no liquid or gaseous medium, Without any environmental pollution problems, adjusting the working power of the refrigeration device can adjust the cooling rate or even switch to the heating working state, so as to achieve precise temperature control.

3. Micro-elements made of thermoelectric materials are widely used in the preparation of micro-power supply, micro-zone cooling, optical communication laser diode and infrared sensor temperature adjustment system.

4. Classified by working temperature, thermoelectric generators can be divided into three categories: high-temperature thermoelectric generators, medium-temperature thermoelectric generators and low-temperature thermoelectric generators. The typical material used in high-temperature thermoelectric generators is SiGe alloy, the working temperature of its hot surface is about 1000℃; the typical material used in medium-temperature thermoelectric generators is PbTe, and its hot surface working temperature is about 500℃; the typical materials used in low-temperature thermoelectric generators are BiTe, the working temperature of its hot surface is about 200~300℃.

5. According to the composition of the material, it can be divided into oxide thermoelectric materials, filled conductive polymer composite materials, nano thermoelectric materials, superlattice thermoelectric materials, quasicrystalline thermoelectric materials, cage compound thermoelectric materials, low-dimensional thermoelectric materials, and functions Gradient thermoelectric materials and so on.

6. Metal oxides generally have high thermal and chemical stability, can be used in high temperature and oxygen atmosphere, and most of the oxides are non-toxic, non-polluting, environmentally friendly, long service life, simple preparation, low cost, etc.

7. Advantages, the application potential in the high-temperature industry is great, and it is an environmentally friendly thermoelectric material. The disadvantage is that the conductivity is too low, which limits the practical application of the material.

8. The future research goal will be to improve the conductivity of the material or to find a material with high conductivity. Oxide thermoelectric materials can also be used in fields such as high-performance hydrogen sensors, solar power generation, high-performance receivers, and miniature short-range communication devices.

9. Conductive polymer composite materials have the advantages of low price, light weight and good flexibility. By filling a conductive polymer with a low point conductivity with a high-conductivity skutterudite, a composite material with a complex band structure can be obtained.

10. Since the complex band structure is a necessary condition for high-performance thermoelectric semiconductor materials, after optimization, the existence of a large number of organic-inorganic interfaces increases the chance of phonon reflection and the thermal conductivity will be further reduced. It is possible to prepare high-performance thermoelectric semiconductor materials. Of thermoelectric materials.

11. Nano-thermoelectric materials are an emerging system of thermoelectric materials. With the rapid development of nanoscience and nanotechnology, the research of nano-thermoelectric materials has also attracted the attention of many researchers. When the conventional bulk thermoelectric material is nanosized, due to the interface effect and quantum effect of the nanomaterial, the thermal conductivity of the material can be reduced without significantly reducing the point conductivity, thereby obtaining a larger thermoelectric figure of merit. At the same time, nanomaterials can also adjust doping more conveniently, which is conducive to further exploration.

12. Superlattice material is a semiconductor compound with a multilayer heterostructure, which is formed by alternately growing two kinds of extremely thin semiconductor single crystal films. Since each film generally contains a few to dozens of atomic layers, it has obvious quantum effects, resulting in many new physical properties.

13. Another important feature of superlattice materials is the periodicity in many interfaces and structures, which helps increase phonon scattering, and at the same time, the increase in electron scattering on the surface is less, so lower thermal conductivity and higher electrical conductivity can be obtained. s material.

14. Quasicrystalline materials are crystal-like materials that do not have translational symmetry, and usually have symmetry axes that crystals do not have, such as five-, ten- and twelve-fold rotation axes. Quasicrystals and superconductors were listed as two important advances in condensed matter physics in the 1980s. Since their discovery, research on their structure and physical properties has made significant progress. Due to the particularity of the material structure of the quasicrystalline material, the particularity of its electronic structure is caused.

15. The quasicrystalline material has an unusual wide temperature adaptability. It is different from the traditional semiconductor conduction mechanism. Its thermoelectric potential and electrical conductivity increase with the increase of temperature, while the thermal conductivity increases gently with the increase of temperature. Some quasicrystalline materials also have a porous structure, which is also beneficial to reduce the thermal conductivity of the material. Compared with ordinary alloys, the thermal conductivity of quasicrystalline materials is more than two orders of magnitude lower than that of ordinary alloys, and the quality of quasicrystalline samples is better.

16. The more perfect the structure, the lower its thermal conductivity, which makes quasicrystals very advantageous as thermoelectric materials. In addition, quasicrystals also have many other excellent physical properties, such as corrosion resistance, oxidation resistance, high hardness, and thermal stability. In short, as an emerging material system, quasicrystalline materials exhibit many excellent properties and have good application prospects in thermoelectric power generation and electric refrigeration.

17. Electric refrigeration has been used in biological and medical instruments for more than 20 years. With its advantages of no noise, no vibration, small size and convenient use, a series of new products have been successfully developed, such as PCR instrument, Ventilator air pump, cryo scalpel, cold table for tissue sectioning, etc. Another important application of electric refrigeration is to provide a low temperature environment for the use of superconducting materials. Since the application of high-temperature superconducting material devices depends on the refrigeration technology, the current refrigeration uses refrigerants (such as liquid helium, liquid nitrogen), which need to be supplemented frequently, which is very inconvenient, and complicated refrigeration facilities must be used.

18. Therefore, if thermoelectric materials with good performance in the low temperature region (below the liquid helium temperature) can be obtained, it will promote the rapid development of superconducting technology. In general, there are still many problems in the application of thermoelectric power generation and electric refrigeration technology that have not been overcome. The application of thermoelectric devices has the disadvantages of low efficiency and high cost. Therefore, electric refrigeration and power generation are mainly used in applications that do not take energy conversion efficiency as the basis. The main consideration in the occasion. With the development of high-performance thermoelectric materials and the development of thermoelectric technology, it is believed that the application of thermoelectric devices will become more extensive.

This article was written by Longchang Chemical R&D Department. If you need to copy and reprint, please indicate the source.

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