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Thermoelectric materials refer to the green functional materials that directly convert heat energy and electric energy through the movement of carriers inside the material. The main characteristics of the thermoelectric materials are the pollution-free environment and the diversity of energy utilization, which are expected to alleviate the two major problems facing humanity. - Energy crisis and environmental pollution. To evaluate the performance of thermoelectric materials, the thermoelectric value formula is usually used: ZT = TS2σ/κ, where T is the absolute temperature, S is the Seebeck coefficient of the material, σ is the conductivity, and κ is the total thermal conductivity. Among them, S2σ is also called the power factor PF, which is used to characterize the electrical properties of thermoelectric materials. The thermal conductivity κ is composed of lattice thermal conductivity (κL) and electronic thermal conductivity (κE). However, these parameters (S, σ, κ) have a mutual dependence and mutual restraint relationship. Therefore, how to design and synthesize a new type of high-efficiency thermoelectric material has become a hotspot and a difficult point in the field.
State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences The Wu Liming Research Group, under the funding of the National Natural Science Foundation of China under the auspices of the National Natural Science Foundation of China and Associate Fellow Lin Hua, cooperated with scholars from Northwestern University and other institutions. A new type of high-efficiency thermoelectric material CsAg5Te3 was found. Studies have shown that the compound has an ultra-low lattice thermal conductivity (< 0.20 W/K/m, which is the lowest value of the thermoelectric material with the same level of performance), and its thermoelectric figure of merit ZT reaches 1.5 at 727K. Theoretical calculations show that this ultra-low lattice thermal conductivity is attributed to a new type of scattering mechanism that has never been discovered before, namely, the concerted rattling of different Ag coordination in three-dimensional pore structure. This research provides new directions and ideas for exploring new types of high-efficiency thermoelectric materials. The relevant research work applied for Chinese invention patents (201410837415.4) and international PCT patents (PCT/CN2014/095376), and was published in German Applied Chemistry under the title of Concerted Rattling in CsAg5Te3 Leading to Ultralow Thermal Conductivity and High Thermoelectric Performance. Chem. Int. Ed., 2016, 55, DOI: 10.1002/anie.201605015).
Previously, the research group designed and synthesized a thermoelectric material AxRE2Cu6-xTe6 (A=K–Cs; RE=La–Nd) with dual ion tunneling (Chem. Mater. 2011, 23, 4910–4919.); using co-doping Instead of using In4PbxSnySe3 for superior thermoelectric performance (Adv. Mater. 2013, 25, 4800-4806.), a layered thermoelectric material TmCuTe2 was obtained by the “ion cutting†method (Chem.-Eur. J. 2014, 20, 15401-15408. (Hot Paper); found a superionic thermoelectric material Ag1-xCuSe (Inorg. Chem. 2015, 54, 867-871.).
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