Facile synthesis of ultrasmall stannic oxide nanoparticles as anode materials with superior cyclability and rate capability for lithium-ion batteries

摘要

Ultrasmall monodisperse stannic oxide (SnO _(2) ) nanocrystals (diameter around 4 nm) with high-performance lithium storage are successfully synthesized via a simple calcination process, during which SiO _(2) mesoporous nanotubes (SiO _(2) -MNT) are used to play an important role in restraining the growth and aggregation of the nanocrystals. As a kind of anode material for lithium-ion batteries, the as-prepared SnO _(2) nanocrystals show an excellent electrical performance with a super high reversible capacity of 816 mA h g ~(?1) over 200 charge/discharge cycles at a current density of 160 mA g ~(?1) . Moreover, when the current density rises to 3200 mA g ~(?1) , the capacity is still as high as 550 mA h g ~(?1) , and it can be recovered to 816 mA h g ~(?1) simultaneously when the current density turns back to 80 mA g ~(?1) . These results suggest that the obtained SnO _(2) nanocrystals can achieve a completely reversible transformation from Li _(4.4) Sn to SnO during discharging ( i.e. , Li is extracted by dealloying and a reversible conversion reaction, generating 6.4 electrons). The superior electrochemical performance can be ascribed to the ultrafine particle size of SnO _(2) , which promotes the reactive activity and alleviates the volume change of the anode composite during charge/discharge cycling.