Date: January 25, 2019 ǀ 13:00
Location: TUM-IAS Auditorium (ground floor), Lichtenbergstraße 2 a, 85748 Garching
Organization: TUM-IAS and Rudolf Diesel Industry Fellow Dr. Filippo Maglia (BMW Group)
Admission is free. No registration required.
We will present two talks:
Title: Thermal and structural stabilities of LixCoO2 cathode for Li secondary battery studied by a temperature programmed reduction (Do-Hyun Jung, Nurzhan Umirov, Taekeun Kim, Zhumabay Bakenov, Jun-Sik Kim, Sung-Soo Kim)
Speaker: Prof. Sung-Soo Kim, Chungnam National University/ Nazarbayev University.
Abstract:
Temperature programmed reduction (TPR) method was introduced to analyze the structural change and thermal stability of LixCoO2 (LCO) cathode material. The reduction peaks of delithiated LCO clearly represented the different phases of LCO. The reduction peak at a temperature below 250 °C can be attributed to the transformation of CoO2–like to Co3O4–like phase which is similar reduction patterns of CoO2 phase resulting from delithiation of LCO structure. The 2nd reduction peak at 300~375 °C corresponds to the reduction of Co3O4–like phase to CoO-like phase.
TPR results indicate the thermal instability of delithiated LCO driven by CoO2-like phase on the surface of the delithiated LCO. In the TPR kinetics, the activation energies (Ea) obtained for as-synthesized LCO were 105.6 and 82.7 kJ mol-1 for Tm_H1 and Tm_H2, respectively, whereas Ea for the delithiated LCO were 93.2, 124.1 and 216.3 kJ mol-1 for Tm_L1, Tm_L2 and Tm_L3, respectively. As a result, the TPR method enables to identify the structural changes and thermal stability of each phase and effectively characterize the distinctive thermal behavior between as-synthesized and delithiated LCO.
Title: High Performance Cathode Materials for Lithium-Sulfur Batteries
Speaker: Prof. Zhumabay Bakenov, National Laboratory Astana, Nazarbayev University.
Abstract:
Lithium-ion batteries (LIBs) are leading the path for power source for various portable applications and electric vehicles, which is due to their excellent electrochemical performance. LIBs are very promising batteries large scale storage as well such as renewable energy systems and energy backup devices. However, high cost, safety and environmental concerns remain the main factors limiting their wider applications. The hot topic of research in direction to overcome these problems, ‘beyond of lithium batteries’, are lithium-sulfur batteries. In our Research Group we develop high performance cathode materials for such batteries. Main results of these works will be presented at the seminar.