Talk given by Dr. Torsten Brezesinski KIT/BASF Joint Laboratory BELLA Institute of Nanotechnology KIT Abstract: The development of advanced battery technologies is very important as this will help accelerate the transition to a sustainable energy future. With a theoretical specific capacity of 1673 Ah/kg, elemental sulfur is one of the most promising cathode active materials for high-energy-density lithium batteries.[1] However, despite the progress made in the past couple of years, there are still many open questions and issues related to stability and safety that need to be addressed before commercialization of Li-S cells can be contemplated. Major issues include capacity degradation and gassing due to polysulfide shuttle and electrolyte decomposition, respectively. In this talk, I will focus first on the use of (silica-templated) hierarchical N-rich carbon to trap lithium polysulfides in Li-S cells. Sulfur/N-rich carbon cathodes exhibit stable performance and display good cyclability with areal capacities > 2 mAh/cm2.[2] Then, I discuss gas evolution in cells with diglyme-based electrolyte and evaluate the important function of LiNO3 as a stabilizing additive. Furthermore, I will show that hierarchical N-rich carbon is also a promising host for other redox active materials. Specifically, atomic layer deposition is a powerful means to chemically modify it for the construction of long-life batteries with high-performance stability.[3] The second part of the talk is on polymer-templated mesostructured metal oxide thin films. Advances in block copolymer templating have enabled the synthesis of many important phases and materials with different ordering lengths.[4] However, the preparation of mixed-metal oxides with both a well-defined mesoporous morphology and nanocrystalline walls is still very challenging. I will specifically focus on current and future projects in this field and show, for example, that also rather complex oxides such as La1–xCaxMnO3 and LiFe5O8 can be produced in thin film format by sol-gel dip-coating using tailor-made polymer structure-directing agents.[5] These materials can store charge via topotactic Li insertion and double layer charging, respectively, which allows for the intriguing possibility of modulating the magnetization in a reversible manner and might help better understand Faradaic surface processes.[6] Collectively, I will demonstrate that the integration of nanoscale porosity with texture-specific properties paves the way to broaden the scope of application of mesostructured metal oxides, particularly when considering the wealth of opportunities for novel device design. [1] S. Evers, L. F. Nazar, Acc. Chem. Res. 46, 1135 (2013). [2] A. Schneider, C. Weidmann, C. Suchomski, H. Sommer, J. Janek, T. Brezesinski. Chem. Mater. 27, 1674 (2015). [3] C. Reitz, B. Breitung, A. Schneider, D. Wang, M. von der Lehr, T. Leichtweiß, J. Janek, H. Hahn, T. Brezesinski, ACS Appl. Mater. Interfaces DOI: 10.1021/acsami.5b12361 (2016). [4] C. Sanchez, C. Boissiere, D. Grosso, C. Laberty, L. Nicole, Chem. Mater. 20, 682 (2008). [5] C. Reitz, P. M. Leufke, R. Schneider, H. Hahn, T. Brezesinski, Chem. Mater. 26, 5745 (2014). [6] T. Brezesinski, J. Wang, S. H. Tolbert, B. Dunn, Nat. Mater. 9, 146 (2010).

This event is part of the eventgroup INT Talks

Homepage
https://www.int.kit.edu/events.php

Speaker
Dr. Torsten Brezesinski

Institute of Nanotechnology, KIT
http://www.int.kit.edu/staff_709.php

Organizer
Prof. Dr. Jürgen Janek
Battery and Electrochemistry Laboratory (BELLA)
Karlsruher Institut für Technologie und Justus-Liebig-Universität Gießen
Karlsruhe und Gießen
Mail: juergen janek ∂does-not-exist.kit edu
https://www.int.kit.edu/2051_645.php

Targetgroup
Interested / Everyone