Stirring-enabled formation of homogenous sub-50 nm silicon nanoparticles with a modified alumino-reduction of silica as high-performance anode materials

Silicon (Si) nanoparticles hold considerable potential for high-energy-density lithium-ion batteries (LIBs) due to their extraordinarily high capacity and good endurance of volume expansion. Although many synthesis techniques have been established to produce homogeneous Si nanoparticles, such as laser pyrolysis, plasma treatment and electrochemical etching, scaling up their production remains a significant challenge due to intricate procedures, stringent conditions, or expensive precursors involved in above processes. In this study, we introduce a modified alumino-reduction of silica in molten salts to synthesize sub-50 nm Si nanoparticles. Notably, this method operates under an ambient atmosphere and requires only a mild temperature range of 250-300 degrees C. Thanks to sufficient mass transport by rigorous stirring, the resulting nanoparticles demonstrate a uniform size distribution. The minuscule size and even distribution enable Si-nanoparticles-based anode to exhibit remarkable capacity and outstanding cycling stability. Specifically, a high reversible capacity of 1120.2 mA h g-1 is achieved after 500 cycles at 4 A g-1. We further demonstrate that these Si nanoparticles can be imbedded in MXene conductive network to form the microspheres to enhance their rate-performance. Overall, this study provides a convenient scalable synthetic route for preparing Si nanoparticles for high-performance LIBs application.