High Performance CoSn2/SnO2/C Nanocomposites for Li-Ion Battery Anodes

CoSn2/SnO2/C nanocomposites were synthesized by a simple mechanical solid-state synthesis method using a disproportionation reaction of SnO and a stable formation of CoSn2. The synthesized CoSn2/SnO2/C nanocomposites were composed of small CoSn2(5–10 nm) and SnO2(∼5 nm) nanocrystallites within amorphous C matrices, whose electrochemical performances were tested for use as Li-ion battery anodes. Additionally, the electrochemical reaction mechanism during Li insertion/extraction was characterized thoroughly using ex situ extended X-ray absorption fine structure analyses. The CoSn2/SnO2/C nanocomposites showed high electrochemical performances with a high reversible initial capacity of 803 mAh g−1, an excellent cycling behavior (571 mAh g−1after 500 cycles), and a fast C-rate performance (approximately 645 mAh g−1at 1C rate and 560 mAh g−1at 3C rate). The high electrochemical performance of CoSn2/SnO2/C nanocomposites demonstrated its promise as a new high-performance Li-ion battery anode.