One-step synthesis of nanoporous silicon @ graphitized carbon composite and its superior lithium storage properties

Nanoporous silicon @ graphitized carbon (NPSi@C) composites have been reasonably designed and synthesized via one-step magnesiothermic co-reduction using rice husks as the silicon source and CO2 as the carbon source. In the self-assembly process, the nano-silicon prepared from rice husk-derived SiO2 is made into a porous structure and uniformly recombined with graphitized carbon formed by CO2 reduction at low temperature (680 °C). The nanoporous structure has contributed to accommodate the large volume effect of activated silicon and provides sufficient channels for the transfer of lithium ions. Furthermore, the graphitized carbon layers effectively enhance the electrical conductivity and coulombic efficiency of the composites, which is conducive to the improvement of electrochemical performance. The optimized NPSi@C composite exhibits superior lithium storage properties with the initial coulombic efficiency of 41.0% and the reversible specific capacity of 681.8 mA h g−1 after 100 cycles at 0.2 A g−1. This study suggests a simple, low-cost, and scalable strategy, which maximizes the advantages of traditional magnesiothermic reduction, to the preparation of Si/C composites as the most promising alternative anode materials for lithium ion batteries.