Facile synthesis of ultrafine CoSn2 nanocrystals anchored on graphene by one-pot route and the improved electrochemical Li-storage properties

In this work, we succeeded in the synthesis of a CoSn2-nanocrystals/graphene-nanosheets (CoSn2/G) hybrid by a facile in situ one-pot solvothermal route. X-ray diffraction, X-ray photoelectron spectroscopy and Raman spectra results revealed the formation of CoSn2 and the reduction of graphite oxide (GO) to graphene during the one-pot process. Transmission electron microscopy observation indicated that the spherical CoSn2 nanocrystals, with a uniform size of 2-4 nm, are anchored on graphene. The electrochemical tests showed that the CoSn2/G hybrid exhibits obviously improved electrochemical properties compared to the bare Co-Sn alloy prepared by a similar route in the absence of GO, even though the content of graphene is only 7.2 wt%. The enhancement in the electrochemical properties could be attributed to the introduction of graphene that not only constructs two-dimensional conductive networks but also disperses and confines the CoSn2 nanocrystals, in addition to the buffering effect for the large volume changes.