Title: Architecture of copper sulfide compound boosting thermoelectric performance

Abstract

Based on the development of high-performance necessity and urgency of the thermoelectric conversion material, copper sulfide has been regarded as a promising thermoelectric material with relatively high thermoelectric performance and abundant resources. The low intrinsic thermal conductivity and high electrical transport of these materials are born out of the “phonon liquid electron-crystal” structure between the copper and chalcogens. However, three thermoelectric parameters, Seebeck coefficient, electrical conductivity, thermal conductivity, are interrelated with each other. To further improve the thermoelectric properties of copper sulfides must be decoupled these parameters. We discuss the strategies for designed architecture to improve the thermoelectric performance of copper sulfides based on reducing lattice thermal conductivity of single-component material and tuning compositions for optimizing thermoelectric properties. Copper sulfide compound, including the compound structure of multiscale architecture engineered Cu2-xS at different mass ratios and carbon-encapsulated Cu2-xS, synthesized by a room-temperature wet chemical method. The observed electrical conductivity in the multiscale architecture-engineered Cu2-xS is four times as much as that of the Cu2-xS sample at 800 K, which is attributed to the potential energy filtering effect at the new grain boundaries. Moreover, the multiscale architecture in the sintered Cu2- xS increases phonon scattering and results in a reduced lattice thermal conductivity of 0.2 W•m 1•K-1 and figure of merit (zT) of 1.0 at 800 K. The electrical conductivity of Cu2−xS@C compound increases by approximately 50% compared to that of the pure Cu2−xS sample, and can be attributed to an increase in carrier concentration. Phonon scattering interface formation and superionic phase of Cu2−xS@C results in very low lattice thermal conductivity of 0.22 W•m−1•K−1 and maximum thermoelectric zT of 1.04 at 773 K. The results confirmed that these two strategies are effective for the enhancement of thermoelectric performance.

Biography

Chen studied Condensed Matter Physics at Central China Normal University, China and graduated as MS in 2012. She received her PhD. degree in nanomaterials engineering at the Institute for Superconducting and Electronic Materials (ISEM), University of Wollongong, Australia in 2016. Then she worked the School of Physics and Mechanical & Electrical Engineering, Hubei University of Education, China and carried out her research of copper chalcogenide thermoelectric materials in State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Materials Science and Engineering, Donghua University as a post-doctorate from March 2017 to December 2019. Her research focuses on the design and synthesis of novel copper chalcogenides nanostructures for energy conversion and storage. She undertook the National Natural Science Foundation of China (51702091), the Natural Science Foundation of Hubei Province, China (2017CFB192), and the China Postdoctoral Science Foundation (2017M621320).