Ordered-Disordered Material as High Efficiency Thermoelectrics

• Applicant: Professor Dr. Robert Svendsen, since 3/2018
• Subject Area: Theoretical Condensed Matter Physics
• Term: from 2015 to 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 280348963

Thermoelectric devices offer an attractive pathway for addressing an important niche in the globally growing landscape of energy demand, since they can convert heat and, in particular waste-heat, to electricity, the highest form of energy in terms of thermodynamic quality. The energy conversion efficiency of thermoelectrics is characterized by the figure of merit, ZT. In the past decades, searching for high efficiency thermoelectrics has been guided by the concept of "phonon glass electron crystal", i.e. an ideal thermoelectric material should have high carrier mobility and low thermal conductivity. Although along this line remarkable progress already advances ZT to ~2.0, this value is still well below what is needed for thermoelectrics to compete with other electricity producing methods. With the existing state of the art as a starting point, this proposal aims at performing fundamental theoretical/computational investigations to explore the next frontier of thermoelectrics (ZT ~3.0) through the new concepts of "phonon liquid electron crystal", where the combination of liquid-like ions and a crystalline sublattice yields intrinsically very low lattice thermal conductivity. The novelty of the scientific work involved in this project manifests itself in that, we tackle the thermal transport mechanism of a special type of materials that combine ordered crystalline sublattice and kinetically disordered ions as a whole. Such mechanism is crucial to the relevant engineering applications but has not been touched by material physicists so far. The challenge of this project resides in the conceivable failure of the analysis techniques, although mature for traditional fully solid state thermoelectrics, when being applied directly to the new ionic systems. The overall goal of this project is to advance the fundamentals underlying the thermal transport properties of some representative ionic systems and rationally performed nanostructuring as novel materials and strategy for high efficiency thermoelectrics. Closely linked and interdependent classical molecular dynamics simulations and ab initio based anharmonic lattice dynamics and Boltzmann transport equation are proposed as approaches to this end. The result of these investigations is likely to provide a major advancement to the fundamental understanding and rational optimizing of ionic based thermoelectric materials, with the potential to make a clear contribution to the energy needs of the future.

• DFG Programme: Research Grants
• Co-Investigators: Dr.-Ing. Tao Ouyang; Dr.-Ing. Xiaoliang Zhang
• Ehemaliger Antragsteller: Professor Dr. Ming Hu, until 2/2018