M. Sc. Fangmu Qu
Supervisors: Ralf Riedel, Magdalena Graczyk-Zajac
Low electronic conductivity and shuttle effect of sulfur (S) hinders its application in Li-S battery . Numerous carbon materials are used as host for solving above issues [2-3]. However, enough robustness for accommodating the volume expansion during cycles is not easy achieved by most of carbon materials. Porous carbon-rich SiCN/SiOC ceramic matrix is a great option for hosting S due to its robust structure stability and good electronic conductivity [4-6]. Now, we synthetized a carbon-rich SiCN ceramics with tailored morphology under different pyrolysis temperature and infiltrate sulfur into the porous ceramic matrices to form SiCN-S composites used for sulfur cathode. Then we investigated their morphology and performance. Under different pyrolysis temperature, SiCN shows different content and morphology, resulting in various electrochemical performance. SiCN ceramic pyrolyzed at 1000 ℃ exhibits best cycle stability compared with others due to it has more amorphous free carbon and nitrogen. Our work shows a new strategy for using ceramic as host material for S in Li-S battery. And in our subsequent works, we will further investigate other factors of the synthesis of SiCN-S composites on electrochemical performance as well as potential of SiOC ceramics served as sulfur host for cathode in Li-S battery.
 H.-J. Peng, J.-Q. Huang, X.-B. Cheng, Q. Zhang, Review on High-Loading and High-Energy Lithium-Sulfur Batteries, Advanced Energy Materials, 7 (2017).
 Y. Zhao, W. Wu, J. Li, Z. Xu, L. Guan, Encapsulating MWNTs into hollow porous carbon nanotubes: a tube-in-tube carbon nanostructure for high-performance lithium-sulfur batteries, Adv Mater, 26 (2014) 5113-5118.
 D. Gueon, J.T. Hwang, S.B. Yang, E. Cho, K. Sohn, D.K. Yang, J.H. Moon, Spherical Macroporous Carbon Nanotube Particles with Ultrahigh Sulfur Loading for Lithium-Sulfur Battery Cathodes, ACS Nano, 12 (2018) 226-233.
 J. Kaspar, M. Graczyk-Zajac, S. Choudhury, R. Riedel, Impact of the electrical conductivity on the lithium capacity of polymer-derived silicon oxycarbide (SiOC) ceramics, Electrochimica Acta, 216 (2016) 196-202.
 M. Graczyk-Zajac, D. Vrankovic, P. Waleska, C. Hess, P.V. Sasikumar, S. Lauterbach, H.-J. Kleebe, G.D. Sorarù, The Li-storage capacity of SiOC glasses with and without mixed silicon oxycarbide bonds, Journal of Materials Chemistry A, 6 (2018) 93-103.
 D. Vrankovic, M. Graczyk-Zajac, C. Kalcher, J. Rohrer, M. Becker, C. Stabler, G. Trykowski, K. Albe, R. Riedel, Highly Porous Silicon Embedded in a Ceramic Matrix: A Stable High-Capacity Electrode for Li-Ion Batteries, ACS Nano, 11 (2017) 11409-11416.