Silicon,due to its ultra high theoretical capacity and low lithium insertion voltage plateau,has been considered as one of t he most promising anodes for high en ergy and po wer density lithium ion batteries(LIBs).However,the rapid capacity degradation,mainly caused by huge volume change during lithium insertion/extraction process,remains a significant challenge prior to practical applications.In this report,different core-shell Si/C nanostructures were synthesized by a magnesium thermal reduction/carbonization method.It has been proved that the synthesized core-shell Si/C nanostructures significantly improved the LIB performance of Si,which is attributed to the synergistic effects of the conductive carbon film and the hollow structure of the core/shell Si/C nanostructures.