Si/Sn-based nanoparticles with various particle sizes are enwrapped in carbon nanofibers to improve the stability of Si/Sn during lithium alloying and dealloying. The composite structure of Si/Sn@carbon fibers is controllably synthesized by electrospinning and heat treatment. The crystal structure, content, and morphologies of Si/Sn@carbon composites are tunable by the carbonization conditions. The electrochemical performance of the composites is improved by the buffer effect of carbon fibers. The sample of SiSnC_800, which the precursor TEOS/SnCl2/PAN, is carbonized at 800 degrees C, delivers a specific capacity of 1347 mAh g(-1) at the second cycles, and retains 1073 mAh g(-1) at 50th cycle. The as-synthesized samples are flexible self-supporting films, which can be directly used as anode materials for lithium ion batteries.