HZB presents research on thermoelectrics
HZB Group at the ICT/ECT2015. From left to right: Dr. Klaus Habicht (Head of the Department for Methods for Characterization of Transport Phenomena in Energy Materials), Dr. Tommy Hofmann, Dr. Katharina Fritsch, Dr. Britta Willenberg, Dr. Katrin Meier-Kirchner
The annual "International Conference on Thermoelectrics (ICT)” and the "European Conference on Thermoelectrics (ECT)” took place together from 29 June to 02 July 2015 in Dresden, Germany. For the first time, HZB participated in this international multidisciplinary meeting. The HZB Department "Methods for Characterization of Transport Phenomena in Energy Materials" headed by Dr. Klaus Habicht presented their research in two talks and one poster.
Dr. Tommy Hofmann presented a talk on the thermoelectric properties of nanostructured silicon which is prepared at HZB by an electrochemical etching process and which is characterized in-house by macroscopic techniques, and by microscopic probes. This material is currently of great interest as silicon is earth-abundant, non-toxic and inexpensive, which distinguishes it from current thermoelectric materials such as Bi2Te3 or PbTe. The nanostructuring of this simple material offers new possibilities to increase the thermoelectric efficiency of the material, for example by reducing the thermal conductivity through the artificial creation of interfaces within the material. The thermal conductivity as macroscopic quantity relates to the transport of lattice vibrations or phonons on the microscopic level, which can be ideally studied using inelastic neutron scattering techniques available at HZB's research reactor BER II.
In the second talk, Dr. Katharina Fritsch gave an overview of the experimental methods for thermoelectrics research applied in the Department, and she presented selected ongoing research projects. Discussed projects ranged from nanostructured silicon to experiments on the lattice dynamics and electronic bandstructure of low-dimensional thermoelectric single crystals as well as structural investigations of skutterudite compounds.
The structure-functionality relationship in skutterudite compounds were also the topic of the poster entitled "Yb-filled skutterudites: a combined macroscopic and microscopic approach", in which Dr. Britta Willenberg presented results of a project realised as cooperation between the Department and the Institute of Materials Research at the German Aerospace Center (DLR) in Cologne.
The meeting was a perfect venue to get feedback on our research projects and to present the experimental facilities and research opportunities at HZB to a large audience from Germany and abroad. Overall, we we were able to attract new potential collaboration partners.
- Porous Radical Organic framework improves lithium-sulphur batteriesA team led by Prof. Yan Lu, HZB, and Prof. Arne Thomas, Technical University of Berlin, has developed a material that enhances the capacity and stability of lithium-sulphur batteries. The material is based on polymers that form a framework with open pores (known as radical-cationic covalent organic frameworks or COFs). Catalytically accelerated reactions take place in these pores, firmly trapping polysulphides, which would shorten the battery life. Some of the experimental analyses were conducted at the BAMline at BESSY II.
- Shedding light on insulators: how light pulses unfreeze electronsMetal oxides are abundant in nature and central to technologies such as photocatalysis and photovoltaics. Yet, many suffer from poor electrical conduction, caused by strong repulsion between electrons in neighboring metal atoms. Researchers at HZB and partner institutions have shown that light pulses can temporarily weaken these repulsive forces, lowering the energy required for electrons mobility, inducing a metal-like behavior. This discovery offers a new way to manipulate material properties with light, with high potential to more efficient light-based devices.
- Lithium-sulphur batteries with lean electrolyte: problem areas clarifiedUsing a non-destructive method, a team at HZB investigated practical lithium-sulphur pouch cells with lean electrolyte for the first time. With operando neutron tomography, they could visualise in real-time how the liquid electrolyte distributes and wets the electrodes across multilayers during charging and discharging. These findings offer valuable insights into the cell failure mechanisms and are helpful to design compact Li-S batteries with a high energy density in formats relevant to industrial applications.