Reactive Spray Drying as a One-Step Synthesis Approach towards Si/rGO Anode Materials for Lithium-Ion Batteries

Lithium-ion batteries with Si anodes are still attracting increasing attention, particularly due to the high specific energy density. The main disadvantage of silicon as anode material is its reduced cell performance in terms of cycling stability. One promising approach to improve this is embedding silicon nanoparticles in a graphene-like matrix via spray drying. All processes described so far need a time- and energy-intensive two-step-synthesis to obtain the graphene-like rGO structure. Here, we present a reactive spray drying process for synthesis of Si/rGO composites. For proper reactor design, the reaction kinetics are investigated by simultaneous thermal analysis in various atmospheres. We can describe thermal decomposition of GO to rGO as a second-order reaction. STA data also show that additional presence of water in the atmosphere due to the one-step synthesis is negligible at temperatures below 600 °C for both the reaction of GO and the additional oxidation of Si. To evaluate the electrochemical performance, the composites are cycled in a half cell setup. Delithiation capacity after cell formation could be raised from 252 mAh g-1 for GO to 327 mAh g-1 for rGO. In addition, we are able to synthesize Si-containing composites suitable for the anode of LiB using our process.