Electrochemical lithiation and de-lithiation of MWNT-Sn/SnNi nanocomposites

Nanocrystalline multi-walled carbon nanotube (MWNT)-Sn and MWNT-SnNi composite anode materials were prepared by chemical reduction of SnCl2 and NiCl2 precursors in the presence of MWNTs. SEM and TEM observations showed that the Sn and SnNi particles are homogeneously dispersed on the MWNT surface and in the MWNT matrix. The electrochemical performance of MWNT-Sn and MWNT-SnNi nanocomposites has been investigated by charge/discharge tests, cyclic voltammetric experiments and the ac impedance technique. The MWNT-Sn and MWNT-SnNi anodes have demonstrated a high first discharge capacity (570 and 512 mA h/g for MWNT-Sn and MWNT-SnNi anodes, respectively), high charge/discharge efficiency in the first cycle (77.5% and 84.1% for MWNT-Sn and MWNT-SnNi anodes, respectively), and good cyclability (0.99 loss%/cycle for MWNT/SnNi anode). A reaction model has been proposed to explain the reaction mechanisms of lithium insertion and extraction in the MWNT-Sn and MWNT-SnNi electrodes.