Silicon Oxycarbide Beads from Continuously Produced Polysilsesquioxane as Stable Anode Material for Lithium-Ion Batteries

Abstract

Silicon oxycarbides are promising anode materials for lithium-ion batteries. In this study, we used the continuous MicroJet reactor technique to produce organically modified silica (ORMOSIL) spheres which were pyrolyzed to obtain silicon oxycarbides. The continuous technique allows the production of large quantities with a constant quality. Different alkoxysilanes were used to produce the silicon oxycarbides with different compositions. Thereby, the amounts of silicon–carbon bonds, as well as the free carbon content, were modified. Electrochemical testing was carried out in 1 M LiPF6 in ethylene carbonate/dimethyl carbonate. A mixture of vinyl- and phenyltrimethoxysilane was identified as the best anode material with a stable performance due to the increased carbon content. The first-cycle delithiation capacity of the most stable material was 922 mA h/g, and the capacity retention after 100 cycles was 83% (767 mA h/g).