Search

CN-121985720-A - Co-sintered segmented thermoelectric material and preparation method thereof

CN121985720ACN 121985720 ACN121985720 ACN 121985720ACN-121985720-A

Abstract

The invention discloses a co-sintering segmented thermoelectric material and a preparation method thereof, wherein the method comprises the following steps of S1, selecting N thermoelectric matrix materials with the same material system but different chemical proportions, weighing raw materials according to the stoichiometric ratio of the N thermoelectric matrix materials, smelting at high temperature to obtain N cast ingots, S2, crushing the N cast ingots to obtain N powder, S3, weighing the N powder according to the mass proportion requirement, obtaining the specific mass proportion through simulation according to the actual temperature difference and the powder quantity, and then filling the powder into a sintering mold step by step according to the room temperature conductivity from low to high or from high to low to perform integrated sintering to obtain the co-sintering segmented thermoelectric material, wherein N is an integer greater than or equal to 2. The method has simple preparation process, flexible structure and capability of integrally sintering to obtain the thermoelectric material with high performance and wide working temperature area.

Inventors

  • JIANG JUN
  • Pang Kaikai
  • ZHANG QIANG
  • CAI JIANFENG
  • GUO ZHE

Assignees

  • 中国科学院宁波材料技术与工程研究所

Dates

Publication Date
20260505
Application Date
20260114

Claims (10)

  1. 1. The preparation method of the co-sintered segmented thermoelectric material is characterized by comprising the following steps of: s1, selecting N thermoelectric matrix materials with the same material system but different chemical proportions, and respectively weighing raw materials according to the stoichiometric ratio of the N thermoelectric matrix materials for high-temperature smelting to obtain N cast ingots; s2, respectively crushing the N cast ingots to prepare powder, so as to obtain N powder; S3, weighing the N kinds of powder according to the mass ratio requirement, simulating the specific mass ratio according to the actual temperature difference and the quantity of the powder, and filling the powder into a sintering mold step by step according to the room temperature conductivity from low to high or from high to low to perform integrated sintering to obtain the co-sintered segmented thermoelectric material, wherein N is an integer greater than or equal to 2.
  2. 2. The method of claim 1, wherein the material system of the thermoelectric base material is one of Bi a Sb 2-a Te 3 、Bi 2 Te 3-b Se b 、Pb 1-c X c Te、PbTe 1-d Z d , wherein 0≤a≤1, 0≤b≤1, x is Na, K, ca or Mn, 0≤c≤0.5, z is I, br, se or S, and 0≤d≤0.5.
  3. 3. The preparation method according to claim 1, wherein in the step S1, the high-temperature smelting is performed at a temperature of 500-1200 ℃ for 0.5-8 hours, and the heating rate is less than 100 ℃ per minute.
  4. 4. The preparation method according to claim 1, wherein the powder preparation method in the step S2 is a ball milling method, the ball milling process is carried out under an inert atmosphere, and the particle size of the obtained powder is 0.1-100 μm.
  5. 5. The preparation method according to claim 1, wherein the sintering method in the step S3 is one selected from hot press sintering, microwave sintering and spark plasma sintering, the sintering temperature is 300-650 ℃, the sintering pressure is 10-80 MPa, and the heat preservation time is 3-20 min.
  6. 6. The preparation method of claim 5, wherein when the material system of the thermoelectric base material is Bi a Sb 2-a Te 3 and a is more than or equal to 0 and less than or equal to 1, the high-temperature smelting temperature in the step S1 is 500-900 ℃ for 1-4 hours, the sintering temperature in the step S3 is 350-450 ℃, the sintering pressure is 40-60 MPa, and the heat preservation time is 3-10 min.
  7. 7. The preparation method of claim 5, wherein when the material system of the thermoelectric base material is Bi 2 Te 3-b Se b and b is more than or equal to 0 and less than or equal to 1, the high-temperature smelting temperature in the step S1 is 500-900 ℃ for 1-4 hours, the sintering temperature in the step S3 is 350-450 ℃, the sintering pressure is 40-60 MPa, and the heat preservation time is 3-10 min.
  8. 8. The preparation method according to claim 5, wherein when the material system of the thermoelectric base material is Pb 1- c X c Te and X is Na, K, ca or Mn, C is more than or equal to 0 and less than or equal to 0.5, the high-temperature smelting temperature in the step S1 is 800-1200 ℃ for 1-8 hours, the sintering temperature in the step S3 is 450-650 ℃, the sintering pressure is 20-80 MPa, and the heat preservation time is 3-20 minutes.
  9. 9. The preparation method according to claim 5, wherein when the chemical formula of the thermoelectric matrix material is PbTe 1- d Z d and Z is I, br, se or S, d is more than or equal to 0 and less than or equal to 0.5, the high-temperature smelting temperature in the step S1 is 800-1200 ℃ for 1-8 hours, the sintering temperature in the step S3 is 450-650 ℃, the sintering pressure is 20-80 MPa, and the heat preservation time is 3-20 minutes.
  10. 10. A co-sintered segmented thermoelectric material prepared by the preparation method of any one of claims 1 to 9.

Description

Co-sintered segmented thermoelectric material and preparation method thereof Technical Field The invention relates to the technical field of thermoelectric materials, in particular to a co-sintered segmented thermoelectric material and a preparation method thereof. Background The thermoelectric technology can directly convert heat energy into electric energy, has the advantages of no mechanical movable parts and no emission of greenhouse gases, and has wide application prospects in the fields of deep space exploration power supply, industrial waste heat utilization and the like. In order to better exploit its advantages, the primary task is to increase the maximum energy conversion efficiency of a thermoelectric device, which is directly related to two factors, namely the average ZT value of the material and the temperature difference across the device. When the temperature difference between the hot end and the cold end of the module is fixed, the average ZT value of the material plays a decisive role. However, thermoelectric materials generally optimize performance only over a fairly limited temperature range beyond which performance can drop dramatically. In recent years, the construction of segmented thermoelectric legs has become the dominant method of improving conversion efficiency by joining two materials with optimal performance in different temperature regions. This provides a way to achieve higher average ZT values over a wider temperature range while maintaining a larger temperature differential throughout the module. The conversion efficiency of the device reaches 12% when the temperature difference is 541 ℃ by adopting a double-section structure of bismuth telluride and skutterudite materials in the journal paper Energy & Environmental Science (2017) 956-963. The adoption of the dual-segment structure of bismuth telluride and germanium telluride materials in journal paper ADVANCED SCIENCE (2025) 2502832 enables the device conversion efficiency to reach 10.4% at a temperature difference of 440 ℃. The adoption of the dual-segment structure of bismuth telluride and half heusler materials in journal paper ADVANCED ENERGY MATERIALS (2020) 2001924 enables the conversion efficiency of the device to reach 12% when the temperature difference is 584 ℃. However, the manufacturing techniques of the above devices suffer from the disadvantage that the alloys used often have significantly different densification temperatures, which makes one-step co-sintering difficult to achieve. Therefore, a metal bond layer is typically introduced, but this increases the number of interfaces by two to four, and these additional interfaces increase contact resistance and contact thermal resistance, complicating the design of the barrier layer and increasing the risk of interface degradation during use. Since the contact resistance between the barrier layer, the thermoelectric material and the electrode directly affects the maximum output power and the maximum conversion efficiency, it is necessary to minimize them. In addition, the mismatch between the physical properties and materials of the metal bond layer at the junction can result in a natural weak point under thermal and mechanical stresses, further compromising the long-term stability and reliability of the device. Disclosure of Invention The invention aims to solve the technical problem of providing a co-sintered segmented thermoelectric material which has simple preparation process, flexible structure and high performance and wide working temperature range, and can be sintered integrally, and a preparation method thereof. The first object of the present invention is to provide a method for preparing a co-sintered segmented thermoelectric material, comprising the steps of: s1, selecting N thermoelectric matrix materials with the same material system but different chemical proportions, and respectively weighing raw materials according to the stoichiometric ratio of the N thermoelectric matrix materials for high-temperature smelting to obtain N cast ingots; s2, respectively crushing the N cast ingots to prepare powder, so as to obtain N powder; s3, weighing the N kinds of powder according to the mass ratio requirement, wherein the specific mass ratio is obtained through simulation according to the actual temperature difference and the powder quantity, and then filling the powder into a sintering mold step by step according to the room temperature conductivity from low to high or from high to low to perform integrated sintering to obtain the co-sintered segmented thermoelectric material, wherein N is an integer greater than or equal to 2. In the scheme, after two or more than two homologous matrix materials with optimal thermoelectric performance in different temperature ranges are ball-milled, powder is paved in a layering way, and integrated sintering is carried out to prepare the segmented thermoelectric material. The preparation method is simple and efficient, has