The effect of tin content to the morphology of Sn/carbon nanofiber and the electrochemical performance as anode material for lithium batteries

摘要

By using electrospinning and carbonization, tin nanoparticles enwrapped in carbon nano-fibers (Sn/C) present high capacity and well cyclic performance. The precursor compositions of SnCl_2 and polyacrylonitrile (SnCl_2/PAN) have a significant effect on the crystal structure, morphology of Sn/C composites, and the electrochemical performance. Along with the increased concentration of tin in the precursors of SnCl_2/PAN, the diameters of the carbonized Sn/C nanofibers are decreased. The samples of SnCl_2/PAN with starting weight ratio 3:2 (Sn3Pan2), 1:1 (Sn1Pan1) and 2:3 (Sn2Pan3) present the initial discharge capacity 977.8, 1329.8, and 1137.0 mAh g~(-1), respectively. In the following cycles, the Sn/C nanofibers present high capacity and well cyclic performance. The sample Sn1Pan1 retains a charge capacity of 741.1 mAh g~(-1) (92% of the initial charge capacity) after 40 cycles. Because the nanoparticles of tin metal are enwrapped in carbon nanofibers, the volume change and aggregation of metal anode are decreased during charging and discharging processes.