Facile synthesis and electrochemical characterization of Sn4Ni3/C nanocomposites as anode materials for lithium ion batteries

Sn4Ni3/C nanocomposites were synthesized by a pyrolyzing–annealing two-step strategy. The phase structure, carbon content and morphology of the nanocomposites were investigated. The results reveal that the crystallinity, carbon structure and purity were enhanced obviously after heat-treatment. Electrochemical performance was evaluated by cyclic voltammograms (CV), galvanostatic discharge/charge and electrochemical impedance spectra (EIS). The annealed Sn4Ni3/C powders deliver an initial charge capacity of 525.2 mA h g−1, 400 mA h g−1 over 10 cycles at 36 mA g−1, >300 mA h g−1 after 40 cycles at 72 mA g−1 and maintain 240 mA h g−1 for 40 cycles at 150 mA g−1. TEM investigation of the cycled electrodes shows the discharge/charge process neither destroyed the structure of nanocomposites nor changed the crystallinity of the materials. So the high capacity and stable cyclability are ascribed to the synergetic effect of ductile nickel and conductive carbon constituent and the influence of heat-treatment.