Nanostructured FeSn2/SnO2-based composites as high-performance anodes for lithium-ion batteries

Abstract

A nanostructured FeSn2/SnO2 composite was directly synthesized using a simple solid-state ball milling synthesis method by exploiting the disproportionation reaction of SnO and the thermodynamically stable formation of FeSn2. The as-synthesized FeSn2/SnO2 composite comprised small (∼10–20 nm) FeSn2 and SnO2 nanocrystallites, and as a lithium-ion battery anode, it exhibited better electrochemical performance than FeSn2 and SnO2. Furthermore, we prepared a C-decorated FeSn2/SnO2 (FeSn2/SnO2/C) composite. Compared to FeSn2/SnO2, FeSn2/SnO2/C contained smaller nanocrystallites of FeSn2 (∼10 nm) and SnO2 (∼5 nm), which were present in the amorphous C matrix and provided enhanced electrochemical performance. The FeSn2/SnO2/C composite had a high reversible initial capacity of 843 mAh·g−1, a stable capacity retention of above 80% after 100 cycles, and a high C-rate performance of ∼610 mAh·g−1 at 3C rate. Moreover, its electrochemical reaction mechanism during lithium insertion/extraction was determined by ex situ extended X-ray absorption fine structure analysis. Owing to their high electrochemical performance, FeSn2/SnO2/C composites are promising as a new high-performance anode material for lithium-ion batteries.